Total synthesis of salinosporamide a and analogs thereof

ABSTRACT

The present invention relates to certain compounds and to methods for the preparation of certain compounds that can be used in the fields of chemistry and medicine. Specifically, described herein are methods for the preparation of various compounds and intermediates, and the compounds and intermediates themselves. More specifically, described herein are methods for synthesizing Salinosporamide A and its analogs from a compound of formula (V).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/697,689, entitled “Total Synthesis of Salinosporamide A and AnalogsThereof,” filed Apr. 6, 2007, and claims priority to U.S. ProvisionalPatent Application Nos. 60/790,168, entitled “Total Synthesis ofSalinosporamide A and Analogs Thereof,” filed Apr. 6, 2006; 60/816,968,entitled “Total Synthesis of Salinosporamide A and Analogs Thereof,”filed Jun. 27, 2006; 60/836,155, entitled “Total Synthesis ofSalinosporamide A and Analogs Thereof,” filed Aug. 7, 2006; 60/844,132,entitled “Total Synthesis of Salinosporamide A and Analogs Thereof,”filed Sep. 12, 2006; and 60/885,379, entitled “Total Synthesis ofSalinosporamide A and Analogs Thereof,” filed Jan. 17, 2007, all ofwhich are incorporated herein by reference in their entireties,including any drawings.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to certain compounds and to methods forthe preparation of certain compounds that can be used in the fields ofchemistry and medicine.

2. Description of the Related Art

Cancer is a leading cause of death in the United States. Despitesignificant efforts to find new approaches for treating cancer, theprimary treatment options remain surgery, chemotherapy and radiationtherapy, either alone or in combination. Surgery and radiation therapy,however, are generally useful only for fairly defined types of cancer,and are of limited use for treating patients with disseminated disease.Chemotherapy is the method that is generally useful in treating patientswith metastatic cancer or diffuse cancers such as leukemias. Althoughchemotherapy can provide a therapeutic benefit, it often fails to resultin cure of the disease due to the patient's cancer cells becomingresistant to the chemotherapeutic agent. Due, in part, to the likelihoodof cancer cells becoming resistant to a chemotherapeutic agent, suchagents are commonly used in combination to treat patients.

Similarly, infectious diseases caused, for example, by bacteria, fungiand protozoa are becoming increasingly difficult to treat and cure. Forexample, more and more bacteria, fungi and protozoa are developingresistance to current antibiotics and chemotherapeutic agents. Examplesof such microbes include Bacillus, Leishmania, Plasmodium andTrypanosoma.

Furthermore, a growing number of diseases and medical conditions areclassified as inflammatory diseases. Such diseases include conditionssuch as asthma to cardiovascular diseases. These diseases continue toaffect larger and larger numbers of people worldwide despite newtherapies and medical advances.

Therefore, a need exists for additional chemotherapeutics,anti-microbial agents, and anti-inflammatory agents to treat cancer,inflammatory diseases and infectious disease. A continuing effort isbeing made by individual investigators, academia and companies toidentify new, potentially useful chemotherapeutic and anti-microbialagents.

Marine-derived natural products are a rich source of potential newanti-cancer agents and anti-microbial agents. The oceans are massivelycomplex and house a diverse assemblage of microbes that occur inenvironments of extreme variations in pressure, salinity, andtemperature. Marine microorganisms have therefore developed uniquemetabolic and physiological capabilities that not only ensure survivalin extreme and varied habitats, but also offer the potential to producemetabolites that would not be observed from terrestrial microorganisms(Okami, Y. 1993 J Mar Biotechnol 1:59). Representative structuralclasses of such metabolites include terpenes, peptides, polyketides, andcompounds with mixed biosynthetic origins. Many of these molecules havedemonstrable anti-tumor, anti-bacterial, anti-fungal, anti-inflammatoryor immunosuppressive activities (Bull, A. T. et al. 2000 Microbiol MolBiol Rev 64:573; Cragg, G. M. & D. J. Newman 2002 Trends Pharmacol Sci23:404; Kerr, R. G. & S. S. Kerr 1999 Exp Opin Ther Patents 9:1207;Moore, B. S 1999 Nat Prod Rep 16:653; Faulkner, D. J. 2001 Nat Prod Rep18:1; Mayer, A. M. & V. K. Lehmann 2001 Anticancer Res 21:2489),validating the utility of this source for isolating invaluabletherapeutic agents. Further, the isolation of novel anti-cancer andanti-microbial agents that represent alternative mechanistic classes tothose currently on the market will help to address resistance concerns,including any mechanism-based resistance that may have been engineeredinto pathogens for bioterrorism purposes.

SUMMARY OF THE INVENTION

The embodiments disclosed herein generally relate to the total synthesisof chemical compounds, including heterocyclic compounds and analogsthereof. Some embodiments are directed to the chemical compound andintermediate compounds. Other embodiments are directed to the individualmethods of synthesizing the chemical compound and intermediatecompounds.

An embodiment disclosed herein relates to a method for synthesizingSalinosporamide A and its analogs through an intermediate compound offormula (V):

One embodiment described herein relates to a method for synthesizing anintermediate compound of formula (V).

Another embodiment described herein relates to a method for synthesizingan intermediate compound of formula (X).

Still another embodiment described herein relates to a method forsynthesizing an intermediate compound of formula (XV).

Yet still another embodiment described herein relates to a method forsynthesizing an intermediate compound of formula (XVII).

One embodiment described herein relates to a method for synthesizingSalinosporamide A and its analogs through an intermediate compound offormula (V).

Another embodiment described herein relates to a method for synthesizingSalinosporamide A and its analogs through an intermediate compound offormula (VI).

Still another embodiment described herein relates to a method forsynthesizing Salinosporamide A and its analogs through an intermediatecompound of formula (X).

Still another embodiment described herein relates to a method forsynthesizing Salinosporamide A and its analogs through an intermediatecompound of formula (Xp).

Yet still another embodiment described herein relates to a method forsynthesizing Salinosporamide A and its analogs through an intermediatecompound of formula (XI).

One embodiment described herein relates to a method for synthesizingSalinosporamide A and its analogs through an intermediate compound offormula (XV).

Another embodiment described herein relates to a method for synthesizingSalinosporamide A and its analogs through an intermediate compound offormula (XVII).

Still another embodiment described herein relates to a method forsynthesizing Salinosporamide A and its analogs through an intermediatecompound of formula (XVIIp).

Yet still another embodiment described herein relates to a method forsynthesizing Salinosporamide A and its analogs through an intermediatecompound of formula (XVIII).

One embodiment described herein relates to a method for synthesizingSalinosporamide A and its analogs through an intermediate compound offormula (XXIII).

Some embodiments described herein relate to the individual methods ofsynthesizing compounds of formula (III), (IV), (VI), (VI), (VII),(VIII), (IX), (X), (XV), (XVI), (XXII), (XXIII), (XXIV), (XXV), (XXVI),(XXVII), (XXVIII) and protected derivatives thereof.

Other embodiments described herein relate to the individual compounds offormula (III), (IV), (VI), (VI), (VII), (VIII), (IX), (X), (XV), (XVI),(XXII) (XXIII) (XXIV), (XXV) (XXVI), (XXVII), (XXVIII) and protectedderivatives thereof.

One embodiment described herein relates to a method of forming acompound of formula (X) from a compound of formula (V) comprising thesteps of: cleaving the carbon-carbon double bond of the compound offormula (V) and cyclizing the cleaved double bond with the tertiaryhydroxy group; transforming —COOR₂ to an aldehyde; and adding R₄ to thealdehyde using an organometallic moiety containing at least one R₄,wherein R₂ and R₄ are described herein

An embodiment described herein relates to a method of forming a compoundof formula (XV) from a compound of formula (X) comprising the steps of:cleaving an aminal group; removing PG₁ and reductively opening thehemiacetal; and forming a four membered lactone ring, wherein PG₁ can bea protecting group moiety described herein. In some embodiments, thecleaving of the aminal group can occur before the removal of PG₁ andreductively opening the hemiacetal, and before the formation of the fourmembered lactone ring. In other embodiments, the cleaving of the aminalgroup can occur after the removal of PG₁ and reductively opening thehemiacetal, but before the formation of the four membered ring.

Another embodiment described herein relates to a method of forming acompound of formula (XVII) from a compound of formula (V) comprising thesteps of: cleaving the carbon-carbon double bond of the compound offormula (V) and cyclizing the cleaved double bond with the tertiaryhydroxy group; and adding R₄ after cyclization with the tertiary hydroxygroup using an organometallic moiety containing at least one R₄, whereinR₄ is described herein;

On embodiment described herein relates to a method of forming a compoundof formula (XXII) from a compound of formula (XVII) comprising the stepsof: cleaving an aminal group; removing PG₁ and reductively opening thehemiacetal; forming a four membered ring via a lactonization reaction;and removing any protecting groups on a ketone, wherein PG₁ can be aprotecting group moiety described herein. In some embodiments, thecleaving of the aminal group can occur before the removal of PG₁ andreductively opening the hemiacetal, and before the formation of the fourmembered ring via a lactonization reaction. In other embodiments, thecleaving of the aminal group is after the removal of PG₁ and reductivelyopening the hemiacetal, but before the formation of the four memberedring via a lactonization reaction.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form part ofthe specification, merely illustrate certain preferred embodiments ofthe present invention. Together with the remainder of the specification,they are meant to serve to explain preferred modes of making certaincompounds of the invention to those of skilled in the art. In thedrawings:

FIG. 1 shows the chemical structure of Salinosporamide A.

FIG. 2 shows a ¹H NMR spectrum of the compound of formula (I-1) inCDCl₃.

FIG. 3 shows a ¹H NMR spectrum of the ester precursor to the compound offormula (II-1) in CDCl₃.

FIG. 4 shows a ¹H NMR spectrum of the protected ester precursor of thecompound of formula (II-1) in CDCl₃.

FIG. 5 shows a ¹H NMR spectrum of the compound of formula (II-1) inCDCl₃.

FIG. 6 a shows a ¹H NMR spectrum of the compound of formula (III-1) inCDCl₃.

FIG. 6 b shows a LC-MS of the compound of formula (III-1).

FIG. 7 a shows a ¹H NMR spectrum of the compound of formula (IV-1) inCDCl₃.

FIG. 7 b shows a NOESY spectrum of the compound of formula (IV-1) inCDCl₃.

FIG. 7 c shows a ¹H NMR spectrum of the compound of formula (IV-1A) inCDCl₃.

FIG. 7 d shows a ¹H NMR spectrum of the compound of formula (IV-1B) inCDCl₃.

FIG. 7 e shows a LC-MS of the compound of formula (IV-1).

FIG. 8 shows a ¹H NMR spectrum of the compound of formula (V-1A) inCDCl₃.

FIG. 9 shows a ¹³C NMR spectrum of the compound of formula (V-1A) inCDCl₃.

FIG. 10 shows a ¹H-¹H COSY NMR spectrum of the compound of formula(V-1A) in CDCl₃.

FIG. 11 shows the crystal structure of the compound of formula (V-1A).

FIG. 12 shows a ¹H NMR spectrum of the compound of formula (VI-1) inCDCl₃.

FIG. 13 shows a ¹H NMR spectrum of the compound of formula (VII-1_(a))in CDCl₃.

FIG. 14 shows a ¹H NMR spectrum of the compound of formula (VII-1_(b))in CDCl₃.

FIG. 15 shows the crystal structure of the compound of formula(VII-1_(b)).

FIG. 16 shows a ¹H NMR spectrum of the compound of formula (VIII-1_(b))in CDCl₃.

FIG. 17 shows a ¹H NMR of the compound of formula (VIII-1_(a)) in CDCl₃

FIG. 18 shows a ¹H NMR spectrum of the compound of formula (IX-1_(b)) inCDCl₃

FIG. 19 shows a ¹H NMR spectrum of the compound of formula (IX-1_(a)) inCDCl₃

FIG. 20 shows a ¹H NMR spectrum of the compound of formula (X-1_(b)B) inCDCl₃

FIG. 21 shows a ¹³C NMR spectrum of the compound of formula (X-1_(b)B)in CDCl₃.

FIG. 22 shows the crystal structure of the compound of formula(X-1_(b)B).

FIG. 23 shows a ¹H NMR spectrum of the compound of formula (X-1_(a)B) inCDCl₃.

FIG. 24 shows a ¹³C NMR spectrum of the compound of formula (X-1_(a)B)in CDCl₃.

FIG. 25 shows a ¹H NMR spectrum of the compound of formula (V-1B) inCDCl₃.

FIG. 26 shows the crystal structure of the compound of formula (V-1B).

FIG. 27 shows a ¹H NMR spectrum of the compound of formula (V-1C) inCDCl₃.

FIG. 28 shows a ¹³C NMR spectrum of the compound of formula (V-1C) inCDCl₃.

FIG. 29 shows a NOESY spectrum of the compound of formula (V-1C) inCDCl₃.

FIG. 30 shows a ¹H NMR spectrum of the compound of formula (XXIX-1) inCDCl₃.

FIG. 31 shows a ¹³C NMR spectrum of the compound of formula (XXIX-1) inCDCl₃.

FIG. 32 shows a ¹H NMR spectrum of the compound of formula (XXIII-1B) inCDCl₃.

FIG. 33 shows a ¹³C NMR spectrum of the compound of formula (XXIII-1B)in CDCl₃.

FIG. 34 shows a ¹H NMR spectrum of the compound of formula (XXIV-1B-Bz)in CDCl₃.

FIG. 35 shows a ¹H NMR spectrum of the compound of formula (XXV-1B-Bz)in CDCl₃.

FIG. 36 shows a ¹³C NMR spectrum of the compound of formula (XXV-1B-Bz)in CDCl₃.

FIG. 37 shows a ¹H NMR spectrum of the compound of formula(XXVp-1B-Bz-TMS) in CDCl₃.

FIG. 38 shows a ¹³C NMR spectrum of the compound of formula(XXVp-1B-Bz-TMS) in CDCl₃.

FIG. 39 shows a ¹H NMR spectrum of the compound of formula (XXVI-1B-Bz)in CD₃OD.

FIG. 40 shows a ¹³C NMR spectrum of the compound of formula (XXVI-1B-Bz)in CD₃OD.

FIG. 41 shows a ¹H NMR spectrum of the compound of formula(XXVIII-1B-TBS) in CDCl₃.

FIG. 42 shows a ¹H NMR spectrum of the compound of formula (XV-1B) inacetone-d₆.

FIG. 43 shows a ¹³C NMR spectrum of the compound of formula (XV-1B) inacetone-d₆.

FIG. 44 shows a ¹H NMR spectrum of the compound of formula (XVI-1B)produced from the compound of formula (XV-1B) produced synthetically inCDCl₃.

FIG. 45 shows a ¹³C NMR spectrum of the compound of formula (XVI-1B)produced from the compound of formula (XV-1B) produced synthetically inCDCl₃.

FIG. 46 shows ¹H NMR spectrum of the compound of formula (XXII-1)produced from the compound of formula (XVI-1B) obtained synthetically inCDCl₃.

FIG. 47 shows ¹H NMR spectrum of the compound of formula (XVI-1A)produced from the compound of formula (XXII-1) obtained synthetically inDMSO-d₆.

FIG. 48 shows a comparison of ¹H NMR spectra of compound (XVI-1A)produced synthetically and from fermentation.

FIG. 49 shows a ¹³C NMR spectrum of the compound of formula (XVI-1A)produced from the compound of formula (XXII-1) obtained synthetically inDMSO-d₆.

FIG. 50 shows a comparison of ¹³C NMR spectra of compound (XVI-1A)produced synthetically and from fermentation.

FIG. 51 shows a ¹H NMR spectrum of cyclohexenyltributyltin in CDCl₃.

FIG. 52 shows a ¹H NMR spectrum of the compound of formula (X-1_(a)) inCDCl₃.

FIG. 53 shows a ¹³C NMR spectrum of the compound of formula (X-1_(a)) inCDCl₃.

FIG. 54 shows a ¹H NMR spectrum of the compound of formula (X-1_(b)) inCDCl₃.

FIG. 55 shows a ¹³C NMR spectrum of the compound of formula (X-1_(b)) inCDCl₃.

FIG. 56 shows the crystal structure of the compound of formula(X-1_(b)).

FIG. 57 shows a plot of the inhibition of the chymotrypsin-like activityof 20S proteasomes by the synthetic and fermentation compounds offormula (XVI-1A).

FIG. 58 shows a plot of the inhibition of the trypsin-like activity of20S proteasomes by the synthetic and fermentation compounds of formula(XVI-1A).

FIG. 59 shows a plot of the inhibition of the caspase-like activity of20S proteasomes by the synthetic and fermentation compounds of formula(XVI-1A).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Numerous references are cited herein. The references cited herein,including the U.S. patents cited herein, are each to be consideredincorporated by reference in their entirety into this specification.

Embodiments of the invention include, but are not limited to, methodsfor the preparation of various compounds and intermediates, and thecompounds and intermediates themselves. In some embodiments, one or moresubstituents, one or more compounds, or groups of compounds can bespecifically excluded in any one or more of the methods or compounds asdescribed more fully below.

Salinosporamide A and its analogs thereof have various biologicalactivities. For example, the compounds have chemosensitizing activity,anti-microbial, anti-inflammation, radiosensitizing, and anti-canceractivity. Studies have been conducted that show Salinosporamide A andits analogs have proteasome inhibitory activity, effect NF-κB/IκBsignaling pathway, and have anti-anthrax activity. Salinosporamide A andseveral analogs, as well as biological activity of the same, aredescribed in U.S. Provisional Patent Applications Nos. 60/480,270, filedJun. 20, 2003; 60/566,952, filed Apr. 30, 2004; 60/627,461, filed Nov.12, 2004; 60/633,379, filed Dec. 3, 2004; 60/643,922, filed Jan. 13,2005; 60/658,884, filed Mar. 4, 2005; 60/676,533, filed Apr. 29, 2005;60/567,336, filed Apr. 30, 2004; 60/580,838, filed Jun. 18, 2004;60/591,190, filed Jul. 26, 2004; 60/627,462, filed Nov. 12, 2004;60/644,132, filed Jan. 13, 2005; and 60/659,385, filed Mar. 4, 2005;U.S. patent application Ser. Nos. 10/871,368, filed Jun. 18, 2004;11/118,260, filed Apr. 29, 2005; 11/412,476, filed Apr. 27, 2006; and11/453,374, filed Jun. 15, 2006; and International Patent ApplicationsNos. PCT/US2004/019543, filed Jun. 18, 2004; PCT/US2005/044091, filedDec. 2, 2005; PCT/US2005/014846, filed Apr. 29, 2005; andPCT/US2006/016104, filed Apr. 27, 2006; each of which is herebyincorporated by reference in its entirety.

Provided herein are methods for synthesizing Salinosporamide A and itsanalogs through an intermediate compound of formula (V):

The compound of formula (V) can be synthesized from readily availablestarting materials, as described herein. The compound of formula (V) maybe subsequently converted to Salinosporamide A or analogs thereof. Forexample Salinosporamide A or analogs thereof may be synthesizedaccording to Scheme A.

For the compounds described herein, each stereogenic carbon can be of Ror S configuration. Although the specific compounds exemplified in thisapplication can be depicted in a particular configuration, compoundshaving either the opposite stereochemistry at any given chiral center ormixtures thereof are also envisioned unless otherwise specified. Whenchiral centers are found in the derivatives of this invention, it is tobe understood that the compounds encompasses all possible stereoisomersunless otherwise indicated.

The term “substituted” has its ordinary meaning, as found in numerouscontemporary patents from the related art. See, for example, U.S. Pat.Nos. 6,509,331; 6,506,787; 6,500,825; 5,922,683; 5,886,210; 5,874,443;and 6,350,759; all of which are incorporated herein in their entiretiesby reference. Examples of suitable substituents include but are notlimited to hydrogen, alkoxy, cycloalkyl, cycloalkenyl, acyl, acylamino,acyloxy, amino, alkyl amino, aminoacyl, aminoacyloxy, oxyacylamino,cyano, halogen, hydroxy, carboxyl, carboxylalkyl, keto, thioketo, thiol,thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclic,heterocyclooxy, hydroxyamino, alkoxyamino, nitro, —SO-alkyl,—SO-substituted alkyl, —SO-aryl, —SO-heteroaryl, —SO₂—H, —SO₂—OH,—SO₂-alkyl, —SO₂-substituted alkyl, —SO₂-aryl and —SO₂-heteroaryl,heteroaryl, boronate alkyl, boronic acid, (OH)₂B-alkyl, phosphate andphosphate esters, phosphonooxy, phosphonooxyalkyl, azido, azidoalkyl,ammonium, carboxyalkyl, a salt of a carboxyalkyl, alkylamino, a salt ofan alkylamino, dialkylamino, a salt of a dialkylamino, alkylthio,arylthio, carboxy, cyano, alkanesulfonyl, alkanesulfinyl,alkoxysulfinyl, thiocyano, boronic acidalkyl, boronic esteralkyl,sulfoalkyl, a salt of a sulfoalkyl, alkoxysulfonylalkyl, sulfooxyalkyl,a salt of a sulfooxyalkyl, alkoxysulfonyloxyalkyl, phosphonooxyalkyl, asalt of a phosphonooxyalkyl, (alkylphosphooxy)alkyl, phosphorylalkyl, asalt of a phosphorylalkyl, (alkylphosphoryl)alkyl, pyridinylalkyl, asalt of a pyridinylalkyl, a salt of a heteroarylalkyl guanidino, a saltof a guanidino, and guanidinoalkyl. Each of the substituents can befurther substituted. The other above-listed patents also providestandard definitions for the term “substituted” that are well-understoodby those of skill in the art.

Whenever a group is described as “optionally substituted” the group maybe unsubstituted or substituted with one or more substituents asdescribed herein.

As used herein, any “R” group(s) such as, without limitation, R, R₁, R₂,R₃, R₄, R₅, R₆, R₇, R₈, R_(A) and R_(B) represent substituents that canbe attached to the indicated atom. An R group may be substituted orunsubstituted. If two “R” groups are covalently bonded to the same atomor to adjacent atoms, then they may be “taken together” as definedherein to form a cycloalkyl, aryl, heteroaryl or heterocycle. Forexample, without limitation, if R_(1a) and R_(1b) of an NR_(1a)R_(1b)group are indicated to be “taken together,” it means that they arecovalently bonded to one another to form a ring:

The term “alkyl,” as used herein, means any unbranched or branched,substituted or unsubstituted, saturated hydrocarbon, with C₁-C₂₄preferred, and C₁-C₆ hydrocarbons being preferred, with methyl, ethyl,propyl, isopropyl, butyl, isobutyl, and tert-butyl, and pentyl beingmost preferred.

The term “alkenyl,” as used herein, means any unbranched or branched,substituted or unsubstituted, unsaturated hydrocarbon containing one ormore double bonds. Some examples of alkenyl groups include allyl,homo-allyl, vinyl, crotyl, butenyl, pentenyl, hexenyl, heptenyl andoctenyl.

The term “alkynyl” as used herein, means any unbranched or branched,substituted or unsubstituted, unsaturated hydrocarbon with one or moretriple bonds

The term “cycloalkyl” refers to any non-aromatic, substituted orunsubstituted, hydrocarbon ring, preferably having five to twelve atomscomprising the ring. Furthermore, in the present context, the term“cycloalkyl” comprises fused ring systems such that the definitioncovers bicyclic and tricyclic structures.

The term “cycloalkenyl” refers to any non-aromatic, substituted orunsubstituted, hydrocarbon ring that includes a double bond, preferablyhaving five to twelve atoms comprising the ring. Furthermore, in thepresent context, the term “cycloalkenyl” comprises fused ring systemssuch that the definition covers bicyclic and tricyclic structures.

The term “cycloalkynyl” refers to any non-aromatic, substituted orunsubstituted, hydrocarbon ring that includes a triple bond, preferablyhaving five to twelve atoms comprising the ring. Furthermore, in thepresent context, the term “cycloalkynyl” comprises fused ring systemssuch that the definition covers bicyclic and tricyclic structures.

The term “acyl” refers to hydrogen, lower alkyl, lower alkenyl, or arylconnected, as substituents, via a carbonyl group. Examples includeformyl, acetyl, propanoyl, benzoyl, and acryl. An acyl may besubstituted or unsubstituted.

In the present context the term “aryl” is intended to mean a carbocyclicaromatic ring or ring system. Moreover, the term “aryl” includes fusedring systems wherein at least two aryl rings, or at least one aryl andat least one C₃₋₈-cycloalkyl share at least one chemical bond. Someexamples of “aryl” rings include optionally substituted phenyl,naphthalenyl, phenanthrenyl, anthracenyl, tetralinyl, fluorenyl,indenyl, and indanyl. An aryl group may be substituted or unsubstituted.

In the present context, the term “heteroaryl” is intended to mean aheterocyclic aromatic group where one or more carbon atoms in anaromatic ring have been replaced with one or more heteroatoms selectedfrom the group comprising nitrogen, sulfur, phosphorous, and oxygen.Furthermore, in the present context, the term “heteroaryl” comprisesfused ring systems wherein at least one aryl ring and at least oneheteroaryl ring, at least two heteroaryl rings, at least one heteroarylring and at least one heterocyclyl ring, or at least one heteroaryl ringand at least one C₃₋₈-cycloalkyl ring share at least one chemical bond.A heteroaryl can be substituted or unsubstituted.

The terms “heterocycle” and “heterocyclyl” are intended to mean three-,four-, five-, six-, seven-, and eight-membered rings wherein carbonatoms together with from 1 to 3 heteroatoms constitute said ring. Aheterocycle may optionally contain one or more unsaturated bondssituated in such a way, however, that an aromatic π-electron system doesnot arise. The heteroatoms are independently selected from oxygen,sulfur, and nitrogen. A heterocycle may further contain one or morecarbonyl or thiocarbonyl functionalities, so as to make the definitioninclude oxo-systems and thio-systems such as lactams, lactones, cyclicimides, cyclic thioimides, cyclic carbamates, and the like. Heterocyclylrings may optionally also be fused to at least other heterocyclyl ring,at least one C₃₋₈-cycloalkyl ring, at least one C₃₋₈-cycloalkenyl ringand/or at least one C₃₋₈-cycloalkynyl ring such that the definitionincludes bicyclic and tricyclic structures. Examples of benzo-fusedheterocyclyl groups include, but are not limited to,benzimidazolidinone, tetrahydroquinoline, and methylenedioxybenzene ringstructures. Some examples of “heterocycles” include, but are not limitedto, tetrahydrothiopyran, 4H-pyran, tetrahydropyran, piperidine,1,3-dioxin, 1,3-dioxane, 1,4-dioxin, 1,4-dioxane, piperazine,1,3-oxathiane, 1,4-oxathiin, 1,4-oxathiane, tetrahydro-1,4-thiazine,2H-1,2-oxazine, maleimide, succinimide, barbituric acid, thiobarbituricacid, dioxopiperazine, hydantoin, dihydrouracil, morpholine, trioxane,hexahydro-1,3,5-triazine, tetrahydrothiophene, tetrahydrofuran,pyridine, pyridinium, pyrroline, pyrrolidine, pyrrolidone, pyrrolidione,pyrazoline, pyrazolidine, imidazoline, imidazolidine, 1,3-dioxole,1,3-dioxolane, 1,3-dithiole, 1,3-dithiolane, isoxazoline, isoxazolidine,oxazoline, oxazolidine, oxazolidinone, thiazoline, thiazolidine, and1,3-oxathiolane. A heterocycle group of this invention may besubstituted or unsubstituted.

The term “alkoxy” refers to any unbranched, or branched, substituted orunsubstituted, saturated or unsaturated ether, with C₁-C₆ unbranched,saturated, unsubstituted ethers being preferred, with methoxy beingpreferred, and also with dimethyl, diethyl, methyl-isobutyl, andmethyl-tert-butyl ethers also being preferred.

The term “cycloalkoxy” refers to any non-aromatic hydrocarbon ringcomprising an oxygen heteroatom, preferably having five to twelve atomscomprising the ring. A cycloalkoxy can be substituted or unsubstituted.

The term “alkoxy carbonyl” refers to any linear, branched, cyclic,saturated, unsaturated, aliphatic or aromatic alkoxy attached to acarbonyl group. The examples include methoxycarbonyl group,ethoxycarbonyl group, propyloxycarbonyl group, isopropyloxycarbonylgroup, butoxycarbonyl group, sec-butoxycarbonyl group,tert-butoxycarbonyl group, cyclopentyloxycarbonyl group,cyclohexyloxycarbonyl group, benzyloxycarbonyl group, allyloxycarbonylgroup, phenyloxycarbonyl group, pyridyloxycarbonyl group, and the like.An alkoxy carbonyl may be substituted or unsubstituted.

The term “(cycloalkyl)alkyl is understood as a cycloalkyl groupconnected, as a substituent, via a lower alkylene. The (cycloalkyl)alkylgroup and lower alkylene of a (cycloalkyl)alkyl group may be substitutedor unsubstituted.

The terms “(heterocycle)alkyl” and “(heterocyclyl)alkyl” are understoodas a heterocycle group connected, as a substituent, via a loweralkylene. The heterocycle group and the lower alkylene of a(heterocycle)alkyl group may be substituted or unsubstituted.

The term “arylalkyl” is intended to mean an aryl group connected, as asubstituent, via a lower alkylene, each as defined herein. The arylgroup and lower alkylene of an arylalky may be substituted orunsubstituted. Examples include benzyl, substituted benzyl,2-phenylethyl, 3-phenylpropyl, and naphthylalkyl.

The term “heteroarylalkyl” is understood as heteroaryl groups connected,as substituents, via a lower alkylene, each as defined herein. Theheteroaryl and lower alkylene of a heteroarylalkyl group may besubstituted or unsubstituted. Examples include 2-thienylmethyl,3-thienylmethyl, furylmethyl, thienylethyl, pyrrolylalkyl, pyridylalkyl,isoxazolylalkyl, imidazolylalkyl, and their substituted as well asbenzo-fused analogs.

The term “halogen atom,” as used herein, means any one of theradio-stable atoms of column 7 of the Periodic Table of the Elements,i.e., fluorine, chlorine, bromine, or iodine, with bromine and chlorinebeing preferred.

As employed herein, the following terms have their accepted meaning inthe chemical literature.

9-BBN: 9-borabicyclo[3.3.1]nonane

BF₃.Et₂O: borontrifluoride diethyl etherate

Bn: benzyl

BnOH: benzyl alcohol

BOPCl: bis(2-oxo-3-oxazolidinyl)phosphinic chloride

t-BuOH: tert-butanol/tert-butyl alcohol

t-BuOK: potassium tert-butoxide

Bz: benzoyl

DMIPS: Dimethyl iso-propylsilyl

ESI: electrospray ionization

EtOAc: ethyl acetate

FDH: formate dehydroganase

GDH: glucose dehydrogenase

ID: internal diameter

IPA: isopropyl alcohol

LC-MS: liquid chromatography-mass spectrometry

LDA: lithium diisopropylamide

MS: mass spectrum

MsCl: methanesulfonyl chloride

NaOMe: sodium methoxide

NaOEt: sodium ethoxide

NMO: N-methylmorpholine N-oxide

NMR: nuclear magnetic resonance

Pb(OAc)₄: lead tetraacetate

PCC: pyridinium chlorochromate

PDC: pyridinium dicromate

PPTS: pyridinium p-toluene sulfonate

PTSA: p-toluene sulfonic acid

RT: room temperature

SAR: structure-activity relationship

TMS: trimethylsilyl

TBS: t-butyldimethylsilyl

TES: triethylsilyl

THF: tetrahydrofuran

TFA: trifluoroacetic acid

TPAP: tetrapropylammonium perruthenate

The terms “organometallic moiety” and “organometallic moieties” as usedherein refer to any chemical compound that contains a metal-elementbond(s) of a largely covalent character. The term “metal” as used hereininclude those elements traditionally classified as metals (e.g.,lithium, magnesium, zinc, and tin) and those elements classified asmetalloids (e.g., boron).

The terms “protecting group moiety” and “protecting group moieties” asused herein refer to any atom or group of atoms that is added to amolecule in order to prevent existing groups in the molecule fromundergoing unwanted chemical reactions. Examples of protecting groupmoieties are described in T. W. Greene and P. G. M. Wuts, ProtectiveGroups in Organic Synthesis, 3. Ed. John Wiley & Sons, 1999, and in J.F. W. McOmie, Protective Groups in Organic Chemistry Plenum Press, 1973,both of which are hereby incorporated by reference. The protecting groupmoiety may be chosen in such a way, that they are stable to the reactionconditions applied and readily removed at a convenient stage usingmethodology known from the art. A non-limiting list of protecting groupsinclude benzyl; substituted benzyl; alkylcarbonyls (e.g.,t-butoxycarbonyl (BOC)); arylalkylcarbonyls (e.g., benzyloxycarbonyl,benzoyl); substituted methyl ether (e.g. methoxymethyl ether);substituted ethyl ether; a substituted benzyl ether; tetrahydropyranylether; silyl ethers (e.g., trimethylsilyl, triethylsilyl,triisopropylsilyl, t-butyldimethylsilyl, or t-butyldiphenylsilyl);esters (e.g. benzoate ester); carbonates (e.g. methoxymethylcarbonate);sulfonates (e.g. tosylate, mesylate); acyclic ketal (e.g. dimethylacetal); cyclic ketals (e.g., 1,3-dioxane or 1,3-dioxolanes); acyclicacetal; cyclic acetal; acyclic hemiacetal; cyclic hemiacetal; and cyclicdithioketals (e.g., 1,3-dithiane or 1,3-dithiolane). As used herein, any“PG” group(s) such as, without limitation, PG₁, PG₂ and PG₃ represent aprotecting group moiety.

The terms “pure,” “purified,” “substantially purified,” and “isolated”as used herein refer to the compound of the embodiment being free ofother, dissimilar compounds with which the compound, if found in itsnatural state, would be associated in its natural state. In certainembodiments described as “pure,” “purified,” “substantially purified,”or “isolated” herein, the compound may comprise at least 0.5%, 1%, 5%,10%, or 20%, and most preferably at least 50% or 75% of the mass, byweight, of a given sample.

The terms “derivative,” “variant,” or other similar term refers to acompound that is an analog of the other compound.

As shown in Schemes 1-4, the starting compounds of formulae (I) and (II)may be synthesized from readily available materials. As shown in Scheme1-1, a compound of formula (I) can be synthesized from a serine estersalt, an aldehyde (e.g. t-butyl aldehyde) and a base (e.g.,triethylamine) at elevated temperatures. In some embodiments, the serineester salt can be a D-serine methylester salt which can form a compoundof formula (I) with the stereochemistry shown in Scheme 1-2.

In some embodiments, a compound of formula (I) can have the structureshown above wherein R₁ can be hydrogen or unsubstituted or substitutedC₁₋₆ alkyl; and R₂ can be hydrogen, or substituted or unsubstitutedvariants of the following: C₁₋₆ alkyl, aryl or arylalkyl. In anembodiment when R₁ is hydrogen, one skilled in the art would recognizethat the stereochemistry at C-4 may not be retained upon conversion of acompound of formula (IV) to a compound of formula (V) shown below. In anembodiment when R₁ is an unsubstituted or substituted C₁₋₆ alkyl, oneskilled in the art would recognize that the stereochemistry at C-4 wouldbe retained upon conversion of a compound of formula (IV) to a compoundof formula (V) shown below. As an example, a compound of formula (I) canhave the following structure and stereochemistry:

A compound of formula (II) can be synthesized according to Schemes 2, 3and 4. The ester precursor of the compound of Formula II can be preparedaccording to Scheme 2, starting with a β-ketoester and a base (e.g.,t-BuOK or NaH) and then adding an allyl halide.

In some embodiments, the ester precursor of the compound of formula (II)can have the structure shown above wherein R can be hydrogen orsubstituted or unsubstituted variants of the following: C₁₋₆ alkyl, arylor arylalkyl; and R₃ can be substituted or unsubstituted variants of thefollowing: C₁₋₆ alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl, C₃₋₆ cycloalkenyl,aryl, or arylalkyl. An exemplary ester precursor is the compound havingthe following structure:

The protected ester precursor of the compound of formula (II) can beprepared according to Scheme 3. The ketone carbonyl of the esterprecursor can be protected using a suitable protecting groupmoiety/moieties, as described herein. One method for protecting theketone carbonyl is shown in Scheme 3.

In some embodiments, the protected ester precursor of the compound offormula (II) can have structure shown in Scheme 3 wherein R can behydrogen or substituted or unsubstituted variants of the following: C₁₋₆alkyl, aryl or arylalkyl; R₃ can be substituted or unsubstitutedvariants of the following: C₁₋₆ alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl,C₃₋₆ cycloalkenyl, aryl, or arylalkyl; each Y can be an oxygen orsulfur; and R_(A) and R_(B) can be each independently selected from thegroup consisting of substituted or unsubstituted variants of thefollowing: C₁₋₆ alkyl, C₂₋₆ alkenyl and C₂₋₆ alkynyl, wherein R_(A) andR_(B) can be optionally bound together to form an optionally substituted5, 6, 7, or 8 membered heterocyclyl.

For example, the ketone carbonyl may be protected by reacting the esterprecursor with 1,2 dihydroxyethane to form a 1,3-dioxolane heterocyclicring as shown below:

As shown in Scheme 4, the protected ester precursor of a compound offormula (II) can then be hydrolyzed to the carboxylic acid equivalentusing an appropriate acid such as TFA or PTSA to form a compound offormula (II).

In some embodiments, a compound of formula (II) can have the structureshown in Scheme 4 wherein R₃ can be substituted or unsubstitutedvariants of the following: C₁₋₆ alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl,C₃₋₆ cycloalkenyl, aryl, or arylalkyl; each Y can be an oxygen orsulfur; and R_(A) and R_(B) can be each independently selected from thegroup consisting of substituted or unsubstituted variants of thefollowing: C₁₋₆ alkyl, C₂₋₆ alkenyl and C₂₋₆ alkynyl, wherein R_(A) andR_(B) can be optionally bound together to form an optionally substituted5, 6, 7, or 8 membered heterocyclyl. As an example, the compound offormula (II) can have the following structure:

A method of preparing a compound of formula (V) from the startingcompounds of formulae (I) and (II) is shown below in Scheme 5.

In step (a) of Scheme 5, a compound of formula (III) can be formed byreacting a compound of formula (I) with a compound of formula (II) undersuitable conditions wherein R₁ can be hydrogen or unsubstituted orsubstituted C₁₋₆ alkyl; R₂ can be hydrogen, or substituted orunsubstituted variants of the following: C₁₋₆ alkyl, aryl or arylalkyl;R₃ can be substituted or unsubstituted variants of the following: C₁₋₆alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl, C₃₋₆ cycloalkenyl, aryl, orarylalkyl; each Y can be an oxygen or sulfur; and R_(A) and R_(B) can beeach independently selected from the group consisting of substituted orunsubstituted variants of the following: C₁₋₆ alkyl, C₂₋₆ alkenyl andC₂₋₆ alkynyl, wherein R_(A) and R_(B) can be optionally bound togetherto form an optionally substituted 5, 6, 7, or 8 membered heterocyclyl.For example, a compound of formula (I) can be added to a mixturecontaining a compound of formula (II), a mild base (e.g., triethylamineor N-methyl piperidine) and an acylating agent such as methanesulfonylchloride, trifluoromethanesulfonyl chloride or chloromethylformate.

As an example, the compounds of formulae (I), (II) and (III) may havethe following structures and stereochemistry:

In one embodiment, the compounds of formulae (I), (II) and (III) canhave the following structures:

The compound of formula (III) can be deprotected to form a compound offormula (IV), as shown in step (b) of Scheme 5, wherein: R₁ can behydrogen or unsubstituted or substituted C₁₋₆ alkyl; R₂ can be hydrogen,or substituted or unsubstituted variants of the following: C₁₋₆ alkyl,aryl or arylalkyl; R₃ can be substituted or unsubstituted variants ofthe following: C₁₋₆ alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl, C₃₋₆cycloalkenyl, aryl, or arylalkyl; each Y can be an oxygen or sulfur; andR_(A) and R_(B) can be each independently selected from the groupconsisting of substituted or unsubstituted variants of the following:C₁₋₆ alkyl, C₂₋₆ alkenyl and C₂₋₆ alkynyl, wherein R_(A) and R_(B) canbe optionally bound together to form an optionally substituted 5, 6, 7,or 8 membered heterocyclyl. One method for removing the ketone carbonylprotecting group (e.g., 1,3-dioxolane) includes reacting a compound offormula (III) with sodium iodide and a Lewis base such as cerium (III)chloride heptahydrate. A second method includes reacting a compound offormula (III) with iodine in acetone at an elevated temperature.Alternatively, a compound of formula (III) can be reacted with lithiumtetrafluoroboride at an elevated temperature to form a compound offormula (IV). If Y is sulfur, the ketone carbonyl protecting group canbe removed using various hydrolytic, oxidative and/or solid-statemethods such as those described and cited in Habibi et al., Molecules,(2003) 8, 663-9, which is incorporated by reference in its entirety.

Exemplary structures and stereochemistry of compounds of formulae (III)and (IV) are shown below:

For example, the compounds of formulae (III) and (IV) can have thefollowing structures:

As shown in step (c) of Scheme 5, treatment of a compound of formula(IV) with an appropriate base (e.g., t-BuOK, NaOMe, NaOEt or LDA) caninduce an intramolecular aldol reaction to form a compound of formula(V) wherein R₁ can be hydrogen or unsubstituted or substituted C₁₋₆alkyl; R₂ can be hydrogen, or substituted or unsubstituted variants ofthe following: C₁₋₆ alkyl, aryl or arylalkyl; and R₃ can be substitutedor unsubstituted variants of the following: C₁₋₆ alkyl, C₃₋₆ cycloalkyl,C₂₋₆ alkenyl, C₃₋₆ cycloalkenyl, aryl, or arylalkyl.

As an example, the compounds of formulae (IV) and (V) may have thefollowing structures and stereochemistry:

More specifically, compounds of formula (V) may adopt one of thefollowing stereochemical structures:

Exemplary structures of compounds formulae (IV) and (V) are shown below:

More specifically, a compound of formula (V) may adopt one of thefollowing stereochemical structures:

A compound of formula (V) can be used to synthesize heterocycliccompounds such as Salinosporamide A and analogs thereof. One method canproceed through a compound of formula (X), which can then be transformedto Salinosporamide A and analogs thereof, as shown in the schemesherein. In an embodiment, a compound of formula (X) can be produced froma compound of formula (V) as shown in Scheme 6.

In step (d) of Scheme 6, the carbon-carbon double bond of the compoundof formula (V) can be oxidatively cleaved and then cyclized to form ahemiacetal with the tertiary hydroxy group to form a compound of formula(VI), wherein R₁ can be hydrogen or unsubstituted or substituted C₁₋₆alkyl; R₂ can be hydrogen, or substituted or unsubstituted variants ofthe following: C₁₋₆ alkyl, aryl or arylalkyl; and R₃ can be substitutedor unsubstituted variants of the following: C₁₋₆ alkyl, C₃₋₆ cycloalkyl,C₂₋₆ alkenyl, C₃₋₆ cycloalkenyl, aryl, or arylalkyl. An exemplary methodfor preparing a compound of formula (VI) includes reacting a compound offormula (V) with a suitable oxidant or oxidant combination, such as OsO₄and NMO for several hours and then adding an additional oxidant (e.g.,NaIO₄ or Pb(OAc)₄) to the reaction mixture. The reaction can be quenchedusing suitable salt solutions.

Exemplary structures and stereochemistry of compounds of formulae (V)and (VI) are shown below:

Examples of compounds of formulae (V) and (VI) are as follows:

If desired, the hemiacetal of a compound of formula (VI) can beprotected by forming an acetal using a protecting group moiety (e.g.benzyl, substituted benzyl, silyl, or methoxylmethyl) to form a compoundof formula (VII), as shown in step (e) of Scheme 6. In some embodiments,R₁, R₂, and R₃ can be the same as described with respect to the compoundof formula (VI); and PG₁ can be a protecting group moiety. Examples ofsuitable protecting group moieties are described herein.

As an example, the compounds of formulae (VI) and (VII) may have thefollowing structures and stereochemistry:

Exemplary structures of compounds of formulae (VI) and (VII) are shownbelow:

As shown in step (f) of Scheme 6, the COOR₂ group of a compound offormula (VII) can be reduced to an alcohol to form a compound of formula(VIII), wherein R₁, R₃, and PG₁ can be the same as described withrespect to the compound of formula (VII). For example, the COOR₂ groupcan be reduced to an alcohol using a suitable reducing reagent (e.g.,diisobutylaluminum hydride, lithium borohydride, lithium aluminumhydride, superhydride) and known techniques.

Exemplary structures and stereochemistry of compounds of formulae (VII)and (VIII) are shown below:

For example, compounds of formulae (VII) and (VIII) can have thefollowing structures:

In step (g) of Scheme 6, the C-5 alcohol of the compound of formula(VIII) can be oxidized using an appropriate oxidizing agent to form thecompound of formula (IX), wherein R₁, R₃, and PG₁ can be the same asdescribed with respect to the compound of formula (VII). For example, analcohol can be oxidized to an aldehyde using an oxidant such asDess-Martin periodinane, TPAP/NMO, Swern oxidation reagent, PCC, or PDC.

Compounds of formulae (VIII) and (IX) may have the following structuresand stereochemistry:

Examples of compounds of formulae (VIII) and (IX) are as follows:

In another embodiment, the COOR₂ group of a compound of formula (VII)can be reduced directly to an aldehyde to give a compound of formula(IX) in a single step.

As shown in step (h) of Scheme 6, a compound of formula (X) can besynthesized by reacting an organometallic moiety containing at least oneR₄ with a compound of formula (IX), wherein R₁, R₃, and PG₁ can be thesame as described with respect to the compound of formula (VII); and R₄can be selected from the group consisting of substituted orunsubstituted variants of the following: C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl,C₂-C₁₂ alkynyl, C₃-C₁₂ cycloalkyl, C₃-C₁₂ cycloalkenyl, C₃-C₁₂cycloalkynyl, C₃-C₁₂ heterocyclyl, aryl, heteroaryl, arylalkyl,heteroarylalkyl, (cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl,acylalkyl, alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido,azidoalkyl, aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of acarboxyalkyl, alkylaminoalkyl, salt of an alkylaminoalkyl,dialkylaminoalkyl, salt of a dialkylaminoalkyl, phenyl, alkylthioalkyl,arylthioalkyl, carboxy, cyano, alkanesulfonylalkyl, alkanesulfinylalkyl,alkoxysulfinylalkyl, thiocyanoalkyl, boronic acidalkyl, boronicesteralkyl, guanidinoalkyl, salt of guanidinoalkyl, sulfoalkyl, salt ofa sulfoalkyl, alkoxysulfonylalkyl, sulfooxyalkyl, salt of asulfooxyalkyl, alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of aphosphonooxyalkyl, (alkylphosphooxy)alkyl, phosphorylalkyl, salt of aphosphorylalkyl, (alkylphosphoryl)alkyl, pyridinylalkyl, salt of apyridinylalkyl, salt of a heteroarylalkyl and halogenated alkylincluding polyhalogenated alkyl. In some embodiments, R₄ can be selectedfrom the group consisting of: substituted or unsubstituted variants ofthe following: C₃-C₁₂ heterocyclyl, aryl, heteroaryl, heteroarylalkyl,(cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl, acylalkyl,alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido, azidoalkyl,aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of a carboxyalkyl,alkylaminoalkyl, salt of an alkylaminoalkyl, dialkylaminoalkyl, salt ofa dialkylaminoalkyl, phenyl, alkylthioalkyl, arylthioalkyl, carboxy,cyano, alkanesulfonylalkyl, alkanesulfinylalkyl, alkoxysulfinylalkyl,thiocyanoalkyl, boronic acidalkyl, boronic esteralkyl, guanidinoalkyl,salt of guanidinoalkyl, sulfoalkyl, salt of a sulfoalkyl,alkoxysulfonylalkyl, sulfooxyalkyl, salt of a sulfooxyalkyl,alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of a phosphonooxyalkyl,(alkylphosphooxy)alkyl, phosphorylalkyl, salt of a phosphorylalkyl,(alkylphosphoryl)alkyl, pyridinylalkyl, salt of a pyridinylalkyl, saltof a heteroarylalkyl and halogenated alkyl including polyhalogenatedalkyl.

A non-limiting list of suitable organometallic moieties includeorganomagnesium compounds, organolithium compounds, organotin compounds,organocuprates compounds, organozinc, and organopalladium compounds,metal carbonyls, metallocenes, carbine complexes, and organometalloids(e.g., organoboranes and organosilanes). In some embodiments, theorganometallic moiety can be selected from the group consisting ofR₄—MgR₇, R₄—ZnR₇, R₄—Li, (R₄)_(p)—B(R₇)_(3-p), and(R₄)_(q)—Sn(R₇)_(4-q); wherein R₇ can selected from the group consistingof halogen, or substituted or unsubstituted variants of the following:alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, isopinocampheyl, hydroxy,alkoxy, and carbonylalkoxy, wherein if more than one R₇ is present, theR₇ groups can optionally be bond together to form an optionallysubstituted cycloalkyl (e.g., 9-BBN), optionally substitutedcycloalkenyl, optionally substituted heteroalkyl or optionallysubstituted heteroalkenyl ring; p can be an integer from 1 to 3; and qcan be an integer from 1 to 4. In an embodiment, the organometallicmoiety is (R₄)_(p)—B(R₇)_(3-p). In certain embodiments, theorganometallic moiety is (R₄)_(p)—B(R₇)_(3-p), wherein R₄ is2-cyclohexenyl. In some embodiments, the organometallic moiety is(R₄)_(p)—B(R₇)_(3-p), wherein R₄ is 2-cyclohexenyl, p is 1, and the twoR₇ groups are taken together to form an optionally substitutedcycloalkyl. In another embodiment, the organometallic moiety is R₄—MgR₇.In certain embodiments, the organometallic moiety is R₄—MgR₇, wherein R₄is 2-cyclohexenyl. In some embodiments, the organometallic moiety isR₄—MgR₇, wherein R₄ is 2-cyclohexenyl and R₇ is a halogen (e.g.,chlorine).

As an example, the compounds of formulae (IX) and (X) may have thefollowing structures and stereochemistry:

As another example, the compounds of formulae (IX) and (X) may have thefollowing structures and stereochemistry.

Exemplary structures of compounds of formulae (IX) and (X) are shownbelow:

Various synthetic routes can be used to transform a compound of formula(X) to Salinosporamide A and analogs thereof. In an embodiment, thesynthesis can proceed through the intermediate compound of formula (XV).Exemplary synthetic routes are shown Schemes 7-1 to 7-5.

As shown in step (i) of Scheme 7-1, the C-5 secondary hydroxy group of acompound of formula (X) can be protected with a suitable protectinggroup moiety to form a compound of formula (Xp), wherein R₁, R₃, R₄ andPG₁ can be the same as described with respect to the compound of formula(X); and PG₂ can be a protecting group moiety. A non-limiting list ofsuitable protecting group moieties that can be used to protect the C-5secondary hydroxy group of a compound of formula (X) include asubstituted methyl ether (e.g. methoxymethyl), a substituted ethyl, asubstituted benzylethyl, tetrahydropyranyl, a silyl ether (e.g.trimethylsilyl, triethylsilyl, triisopropylsilyl, t-butyldimethylsilyl,or t-butyldiphenylsilyl), an ester (e.g. benzoate ester), or a carbonate(e.g. methoxymethylcarbonate). Alternatively, in some embodiments, theC-5 secondary hydroxy group of a compound of formula (X) can remainunprotected, as shown in Scheme 7-2.

Compounds of formulae (X) and (Xp) may have the following structures andstereochemistry:

As examples, compounds of formulae (X) and (Xp) can have the followingstructures:

The aminal of a compound of formula (Xp) can be cleaved using a suitableacid (e.g. triflic acid, HCl, PTSA, PPTS, TFA, camphor sulfonic acid) toform a compound of formula (XIp), as shown in Scheme 7-1. In instancesin which the C-5 secondary hydroxy is unprotected, the same or anotheracid can be used to form a compound of formula (XI) from a compound offormula (X). See Scheme 7-2. The substituents and protecting groupmoieties (R₁, R₃, R₄, PG₁, and PG₂ where applicable) for compounds offormula (XI) and (XIp) can be the same as described with respect to thecompound of formula (Xp).

Exemplary structures and stereochemistry of compounds of formulae (X),(Xp), (XI), and (XIp) are shown below:

As another example, the compounds of formulae (X), (Xp), (XI), and (XIp)can have the following structures and stereochemistry:

For example, compounds of formulae (X), (Xp), (XI) and (XIp) can havethe following structures:

As shown in Scheme 7-1, step (k), the C-15 primary alcohol group of acompound of formula (XIp) can be transformed to R₅ to form a compound offormula (XIIp). Similarly when the C-5 secondary hydroxy group isunprotected, the C-15 primary alcohol group of a compound of formula(XI) can be transformed to R₅ to form a compound of formula (XII). SeeScheme 7-2. R₃, R₄, PG₁, (and PG₂, where applicable) of the compounds offormulae (XII) and (XIIp) can be the same as described with respect tothe compound of formula (Xp); and R₅ can be selected from the groupconsisting of —C(═O)OR₆, —C(═O)SR₆, —C(═O)NR₆R₆, —C(═O)Z wherein each R₆can be independently selected from the group consisting of hydrogen,halogen, or substituted or unsubstituted variants of the following:C₁-C₂₄ alkyl, acyl, alkylacyl, arylacyl, aryl, arylalkyl, p-nitrophenyl,pentafluorophenyl, pentafluoroethyl, trifluoroethyl, trichloroethyl, andheteroaryl; and Z can be a halogen. For example, the primary alcoholgroup can be converted to a carboxylic acid using appropriate oxidationconditions such as Jones oxidation. Alternatively, the carboxylic acidgroup can be prepared from the primary alcohol group of the compound offormula (XI) or (XIp) through an aldehyde. The primary alcohol group ofthe compound of formula (XI) or (XIp) can first be converted to aldehydeusing appropriate oxidant such as Dess-Martin periodinane, TPAP, Swernoxidation reagent, PCC, or PDC and then the resulting aldehyde can beoxidized further to carboxylic acid using appropriate oxidants such as acombination of sodium chlorite/sodium phosphatedibasic/2-methyl-2-butene. If desired, the carboxylic acid can then befurther converted to an ester, a thioester, acid halides (e.g., acidchloride) or an anhydride using an appropriate alcohol, thiol (e.g.,thiophenol, cystine), thionyl or oxalyl chlorides, carboxylic acid(e.g., acetic acid, benzoic acid), and/or anhydride (e.g., aceticanhydride).

As an example, the compounds of formulae (XI), (XIp), (XII) and (XIIp)may have the following structures and stereochemistry:

Other exemplary structures and stereochemistry of the compounds offormulae (XI), (XIp), (XII) and (XIIp) include following structures andstereochemistry:

Exemplary structures of compounds of formulae (XI), (XIp), (XII), and(XIIp) are as follows:

In some embodiments, a compound of formula (XII) can have the structureshown in Scheme 7-2, with the proviso that if a compound of formula(XII) has the structure and stereochemistry of the compound of formula(XII-1A), then R₅ cannot be —C(═O)OR₆, wherein R₆ is t-butyl.

A compound of formula (XIV) can be synthesized by removing anyprotecting group moieties on the compound of formula (XII) and/or (XIIp)to form a compound of formula (XIII) and then cleaving the hemiacetal ofthe compound of formula (XIII). In some embodiments, R₃, R₄, and R₅ ofthe compounds of formulae (XIII) and (XIV) can be the same as describedwith respect to the compound of formula (XIIp). One method forreductively cleaving the hemiacetal can be using a suitable reducingreagent such as sodium borohydride. In one embodiment, the formation ofa compound of formula (XIV) from a compound of formula (XII) or (XIIp)can be accomplished in a single step. In another embodiment, theprotecting group moiety PG₁ on the compound of formula (XII) can beinitially removed to form a compound of formula (XIII) and then theresulting hemiacetal can be reductively cleaved to form a compound offormula (XIV). In another embodiment, the protecting group moieties PG₁and PG₂ on the compound of formula (XIIp) can be removed simultaneouslyor sequentially to form a compound of formula (XIII) and then theresulting hemiacetal can be reductively cleaved to form a compound offormula (XIV). If the protecting group moieties on the compound offormula (XIIp) are removed sequentially, they can be removed in anyorder to form a compound of formula (XIII).

Compounds of formulae (XII), (XIIp), (XIII), and (XIV) may have thefollowing structures and stereochemistry:

Exemplary structures of compounds of formulae (XII), (XIIp), (XIII), and(XIV) are shown below:

In some embodiments, a compound of formula (XIV) can be synthesized byremoving any protecting group moieties on the compound of formula (XII)and/or (XIIp) and reductively cleaving the resulting hemiacetal of thecompound of formula (XIII) with the proviso that if the compound offormula (XII) has the structure and stereochemistry of the compounds offormula (XII-1A), then R₅ cannot be —C(═O)OR₆, wherein R₆ is t-butyl. Inother embodiments, a compound of formula (XIV) can be synthesized byremoving any protecting group moieties on the compound of formula (XII)and/or (XIIp) and reductively cleaving the resulting hemiacetal of thecompound of formula (XIII) with the proviso that if the compound offormula (XIII) has the structure and stereochemistry of the compounds offormula (XIII-1A), then R₅ cannot be —C(═O)OR₆, wherein R₆ is t-butyl.

In one embodiment, a compound of formula (XIII) can have the structureand stereochemistry of a compound of formula (XIII-1A), with the provisothat R₅ cannot be —C(═O)OR₆, wherein R₆ is t-butyl. In an embodiment, acompound of formula (XIV) can have structure shown herein, with theproviso that if the compound of formula (XIV) has the structure andstereochemistry of the compound of formula (XIV-1A), then R₅ cannot be—C(═O)OR₆, wherein R₆ is hydrogen, methyl, or t-butyl.

Finally, in step (m) of Schemes 7-1 and 7-2, a compound of formula (XV)can be formed by treating a compound of formula (XIV) with anappropriate base (e.g., BOPCl/pyridine, triethylamine) to induce alactonization reaction and form the 4-membered heterocyclic ring,wherein R₃, R₄, and R₅ can be same as described with respect to thecompound of formula (XII) or (XIIp). In an embodiment, if R₅ is anester, it can first be transformed to a carboxylic acid, an activatedacid (e.g., acid halide), or an activated ester (e.g., p-nitrophenylester, pentafluorophenyl ester, pentafluoroethyl ester, trifluoroethylester, trichloroethyl ester, a thioester, etc.) before being treatedwith an appropriate reagent to induce the lactonization reaction. Forexample, when R₅ is carboxylic acid, it can be treated with anappropriate base to affect the lactonization reaction. In someembodiments, if R₅ is an amide, it can first be transformed to acarboxylic acid, an activated acid, or an activated ester such as thosedescribed herein before being treated with an appropriate base to inducethe lactonization reaction.

As an example, the compounds of formulae (XIV) and (XV) may have thefollowing structures and stereochemistry:

In another example, the compounds of formulae (XIV) and (XV) may havethe following structures and stereochemistry:

Exemplary structures of compounds of formulae (XIV) and (XV) are asfollows:

In an embodiment, R₅ of the compound of formula (XIV-1A) can be acarboxylic acid. In some embodiments, R₅ of the compound of formula(XIV-1A) can be an activated acid (e.g., acid chloride). In certainembodiments, R₅ of the compound of formula (XIV-1A) can be an activatedester such as p-nitrophenyl ester, pentafluorophenyl ester,pentafluoroethyl ester, trifluoroethyl ester, trichloroethyl ester,thioester, etc. In an embodiment, R₅ of the compound of formula (XIV-1B)can be a carboxylic acid. In some embodiments, R₅ of the compound offormula (XIV-1B) can be an activated acid (e.g., acid chloride). Incertain embodiments, R₅ of the compound of formula (XIV-1B) can be anactivated ester such as p-nitrophenyl ester, pentafluorophenyl ester,pentafluoroethyl ester, trifluoroethyl ester, trichloroethyl ester,thioester, etc.

In some embodiments, a compound of formula (XV) can be synthesized byperforming a lactonization reaction on a compound of formula (XIV) withthe proviso that if the compounds of formulae (XIV) and (XV) have thesame structures and stereochemistry as the compounds of formulae(XIV-1A) and (XV-1A), then R₅ cannot be —C(═O)OR₆, wherein R₆ ishydrogen. In other embodiments, the lactonization reaction includes thefurther proviso that R₆ cannot be methyl or t-butyl when the compoundsof formulae (XIV) and (XV) have the structures and stereochemistry ofthe compounds of formulae (XIV-1A) and (XV-1A). In some embodiments, acompound of formula (XV) can be synthesized by performing alactonization reaction on a compound of formula (XIV) and/or (XIV-A)with the proviso that if R₅ is —C(═O)OR₆, wherein R₆ is hydrogen, methylor t-butyl then R₄ cannot be isopropyl. In an embodiment, a compound offormula (XV) can have the structure shown herein with the proviso thatif the compound of formula (XV) has the structure and stereochemistry ofthe compound of formula (XV-A) and R₃ is methyl then R₄ cannot be2-cyclohexenyl. In some embodiments, a compound of formula (XV) can havethe structure shown herein with the proviso that if R₃ is methyl then R₄cannot be isopropyl, cyclohexyl, or phenyl. In one embodiment, acompound of formula (XV) can have the structure shown herein with theproviso that if the compound of formula (XV) has the structure andstereochemistry of the compound of formula (XV-A) and R₃ is methyl thenR₄ cannot be isopropyl.

A compound of formula (XV) can also be synthesized from a compound offormula (X) as shown in Scheme 7-3. By modifying theprotection/deprotection sequence, a compound of formula (XV) can also beobtained from a compound of formula (X) as shown in Schemes 7-4 and 7-5.

A compound of formula (XXIII) can be synthesized by removing theprotecting group moiety on the compound of formula (X) and reductivelyopening the hemiacetal. The protecting group moiety can be removed usingknown methods and the hemiacetal can be reductively opened using areducing agent (e.g., sodium borohydride). In some embodiments, thesubstituents (and protecting group moiety where applicable) (R₁, R₃, R₄,and PG₁) for compound of formulae (X) and (XXIII) can be selected fromthe following: R₁ can be hydrogen or an unsubstituted or substitutedC₁₋₆ alkyl; R₃ can be substituted or unsubstituted variants of thefollowing: C₁₋₆ alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl, C₃₋₆ cycloalkenyl,aryl, or arylalkyl; R₄ can be selected from the group consisting ofsubstituted or unsubstituted variants of the following: C₁-C₁₂ alkyl,C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₃-C₁₂ cycloalkyl, C₃-C₁₂ cycloalkenyl,C₃-C₁₂ cycloalkynyl, C₃-C₁₂ heterocyclyl, aryl, heteroaryl, arylalkyl,heteroarylalkyl, (cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl,acylalkyl, alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido,azidoalkyl, aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of acarboxyalkyl, alkylaminoalkyl, salt of an alkylaminoalkyl,dialkylaminoalkyl, salt of a dialkylaminoalkyl, phenyl, alkylthioalkyl,arylthioalkyl, carboxy, cyano, alkanesulfonylalkyl, alkanesulfinylalkyl,alkoxysulfinylalkyl, thiocyanoalkyl, boronic acidalkyl, boronicesteralkyl, guanidinoalkyl, salt of guanidinoalkyl, sulfoalkyl, salt ofa sulfoalkyl, alkoxysulfonylalkyl, sulfooxyalkyl, salt of asulfooxyalkyl, alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of aphosphonooxyalkyl, (alkylphosphooxy)alkyl, phosphorylalkyl, salt of aphosphorylalkyl, (alkylphosphoryl)alkyl, pyridinylalkyl, salt of apyridinylalkyl, salt of a heteroarylalkyl and halogenated alkylincluding polyhalogenated alkyl.

Compounds of formulae (X) and (XXIII) may have the following structuresand stereochemistry:

As examples, compounds of formulae (X) and (XXIII) can have thefollowing structures:

If desired, the C-13 primary and C-5 secondary hydroxy groups of acompound of formula (XXIII) can be protected using suitable protectinggroup moieties as described herein to form a compound of formula(XXIVp), as shown in Scheme 7-3. Alternatively, only the C-13 primaryhydroxy group of a compound of formula (XXIII) can be protected to forma compound of formula (XXIV), as shown in Scheme 7-4 and 7-5. In someembodiments, R₁, R₃, and R₄ of the compound of formula (XXIV) can be thesame as described with respect to the compound of formula (X) and PG₃can be a protecting group moiety. In certain embodiments, PG₃ can beselected from the group consisting of substituted or unsubstitutedarylcarbonyls (e.g., benzoyl); substituted or unsubstituted alkylcarbonyl (e.g. acetyl); substituted methyl ether (e.g. methoxymethyl);substituted ethyl ether; substituted or substituted benzyl ether (e.g.benzyl, 4-methoxybenzyl); tetrahydropyranyl ether; silyl ethers (e.g.,trimethylsilyl, triethylsilyl, triisopropylsilyl, t-butyldimethylsilyl,or t-butyldiphenylsilyl); carbonates (e.g. methoxymethylcarbonate); andsulfonates (e.g. mesylate, tosylate. In an embodiment, R₁, R₃ and R₄ ofthe compound of formula (XXIVp) can be the same as described withrespect to the compound of formula (X), and PG₂ and PG₃ can beprotecting group moieties. In some embodiments, PG₃ cannot be an alkylcarbonyl (e.g., —C(═O)CH₂CH₃). In other embodiments, PG₃ cannot be asulfonate (e.g., methylate).

As an example, the compounds of formulae (XXIII), (XXIV), and (XXIVp)may have the following structures and stereochemistry:

Other examples of the structures and stereochemistry of the compounds offormulae (XXIII), (XXIV), and (XXIVp) include the following:

Similar to step (j) of Schemes 7-1 and 7-2, the aminal of a compound offormula (XXIV) can be cleaved using a suitable acid as described hereinto form a compound of formula (XXV). In the case where the C-5 secondaryhydroxy has been protected, the aminal of a compound of formula (XXIVp)can also be cleaved using a suitable acid to form a compound of formula(XXVp). In some embodiments, R₃, and R₄ of the compound of formula (XXV)can be the same as described with respect to the compound of formula(X), and PG₃ can be a protecting group moiety. In some embodiments, R₃and R₄, and PG₂ for compound of formula (XXVp) can be the same asdescribed with respect to the compound of formula (X), and PG₂ and PG₃can be protecting group moieties.

Exemplary structures and stereochemistry of compounds of formulae (XXIV)and (XXV) are shown below:

Additional examples of the structures and stereochemistry of compoundsof formulae (XXIVp), and (XXVp) can be as follows:

Compounds of formulae (XXIV), (XXIVp), (XXV), and (XXVp) may also havethe following structures and stereochemistry:

As shown in Scheme 7-5, the aminal of the compound of formula (XXIV) canfirst be cleaved using one of methods described herein to form acompound of formula (XXV). The C-5 secondary hydroxy group of thecompound of formula (XXV) can then be protected with an appropriateprotecting group moiety to form a compound of formula (XXVp). In someembodiments, R₃, R₄, PG₂, and PG₃ of the compounds of formulae (XXV) and(XXVp) can be the same as described in the preceding paragraphs.

Exemplary structures of compounds of formulae (XXV) and (XXVp) are asfollows:

As an example, the compounds of formulae (XXV) and (XXVp) may have thefollowing structures and stereochemistry:

In an embodiment, the primary alcohol group of the compound of formula(XXV) and/or (XXVp) can be transformed to R₅ to form a compound offormula (XXVI) and/or (XXVIp), respectively (see Schemes 7-3 and 7-4,respectively).

In some embodiments, the compound of formula (XXVp) can be transformeddirectly to a compound of formula (XXVI) as shown in Scheme 7-5. In anembodiment, the protecting group moiety, PG₂, on the compound of formula(XXVp) can be removed simultaneously with the transformation of the C-15primary alcohol to R₅ group to form a compound of formula (XXVI).Alternatively, in an embodiment, PG₂ can be removed before or after thetransformation of the primary alcohol.

The transformation of the C-15 primary alcohol group to an R₅ group canbe achieved using the same or a similar method to the one described instep (k) of Schemes 7-1 and/or 7-2. In some embodiments, R₃, R₄, and R₅of the compounds of formulae (XXVI) and (XXVIp) can be the same asdescribed with respect to the compound of formulae (XII) or (XIIp) ofSchemes 7-1 and/or 7-2, and PG₂ and PG₃ can be a protecting groupmoieties.

Exemplary structures and stereochemistry of the compounds of formulae(XXV), (XXVp), (XXVI), and (XXVIp) can have the following structures andstereochemistry:

Other examples of the structures and stereochemistry of the compounds offormulae (XXV), (XXVp), (XXVI), and (XXVIp) are shown below:

In some embodiments, the protecting group PG₃ on compounds of formulae(XXVI) and (XXVIp) can be removed to form a compound of formulae (XXVII)and (XXVIIp), respectively. See Scheme 7-5. The C-13 primary hydroxy ofthe compounds of formulae (XXVII) and (XXVIIp) can then be reprotectedwith the same or different protecting group. For example, in oneembodiment, a benzoyl group protecting the C-13 hydroxy on a compound offormula (XXVI) or (XXVIp) can be removed and replaced with a TBS or TESprotecting group. Suitable methods for removing protecting groups areknown to those skilled in the art. For example, a benzoyl protectinggroup (PG₃=Bz) can be removed using a suitable base such as K₂CO₃ toform a compound of formula (XXVII) or (XXVIIp).

Exemplary structures and stereochemistry of compounds of formulae(XXVI), (XXVIp), (XXVII) and (XXVIIp) are shown below:

Additional examples of the structures and stereochemistry of compoundsof formulae (XXVI), (XXVIp), (XXVII) and (XXVIIp) can be as follows:

Further examples of the structures and stereochemistry of compounds offormulae (XXVI), (XXVIp), (XXVII) and (XXVIIp) can be as follows:

Using an appropriate base, a compound of formula (XXVIII) and/or(XXVIIIp) can be synthesized via a lactonization reaction from acompound of formula (XXVI) and (XXVIp), respectively. See Schemes 7-3,7-4 and 7-5. In some embodiments, R₃, R₄, R₅ (and PG₂, where relevant)for compounds of formulae (XXVIII) and (XXVIIIp) can be the same asdescribed with respect to the compound of formulae (XXVI) and (XXVIp),and PG₃ can be a protecting group moiety. In some embodiment, R₅ of thecompound of formula (XXVI) or (XXVIp) can be a carboxylic acid. In anembodiment, R₅ of the compound of formula (XXVI) or (XXVIp) can be anactivated acid (e.g., acid chloride). In certain embodiments, R₅ of thecompound of formula (XXVI) or (XXVIp) can be an activated ester such asp-nitrophenyl ester, pentafluorophenyl ester, pentafluoroethyl ester,trifluoroethyl ester, trichloroethyl ester, thioester, etc.

In some embodiments, a compound of formula (XXVIII) can be synthesizedby performing a lactonization reaction on a compound of formula (XXVI)with the proviso that if the compounds of formulae (XXVIII) and (XXVI)have the same structures and stereochemistry of the compounds offormulae (XXVIII-1A) and (XXVI-1A), then R₅ cannot be —C(═O)OR₆, whereinR₆ is hydrogen. In other embodiments, the lactonization reactionincludes the further the proviso that R₆ cannot be methyl or t-butylwhen the compounds of formulae (XXVIII) and (XXVI) have the structuresand stereochemistry of the compounds of formulae (XXVIII-1A) and(XXVI-1A). In an embodiment, the compound of formula (XXVIII) can havethe structure shown herein with the proviso that if R₄ is 2-cyclohexenyland R₃ is methyl, then PG₃ cannot be —C(═O)CH₂CH₃ and/or mesylate. In anembodiment, if the compound of formula (XXVIII) has the structure andstereochemistry of the compound of formula (XXVIII-A) and if R₄ is2-cyclohexenyl and R₃ is methyl, then PG₃ cannot be —C(═O)CH₂CH₃ and/ormesylate.

As an example, compounds of formulae (XXVI) and (XXVIII) can have thestructures and stereochemistry shown below:

Other exemplary structures and stereochemistry of compounds of formulae(XXVIp) and (XXVIIIp) are as follows:

Additional examples of the structures and stereochemistry of compoundsof formulae (XXVI), (XXVIp), (XXVIII), and (XXVIIIp) are shown below:

In the final step shown in Scheme 7-3, 7-4 and 7-5, any protecting groupmoieties can be removed from a compound of formula (XXVIII) and/or(XXVIIIp) to form a compound of formula (XV), respectively. In someembodiments, R₃ and R₄ (and PG₂, where relevant) of the compounds(XXVIII), (XXVIIIp) and (XV) can be the same as described with respectto the compound of formulae (XXVI) or (XXVIp), and PG₃ can be aprotecting group moiety. In another embodiment, the protecting groupsPG₂ and PG₃ can be removed from a compound of formula (XXVIIIp) in astepwise fashion to form a compound of formula (XV); the protectinggroups can be removed in any order. In yet another embodiment, theprotecting groups PG₂ and PG₃ are simultaneously removed from a compoundof formula (XXVIIIp) to form a compound of formula (XV). In anembodiment, a compound of formula (XV) can have the structure shownherein with the proviso that if the compound of formula (XV) has thestructure and stereochemistry of the compound of formula (XV-A) and R₃is methyl then R₄ cannot be 2-cyclohexenyl.

Compounds of formulae (XXVIII), (XXVIIIp) and (XV) can have thefollowing structures and stereochemistry:

In addition, compounds of formula (XXVIII), (XXVIIIp) and (XV) can havethe structures and stereochemistry shown below:

Using an appropriate base, a compound of formula (XV) can also besynthesized via a lactonization reaction from a compound of formula(XXVII), as shown in Scheme 7-5, or lactonization reaction from acompound of formula (XXVIIp) followed by deprotection. In someembodiments, R₃, R₄, R₅, (and PG₂, where relevant) for the compounds offormulae (XXVII), (XXVIIp), and (XV) can be the same as described withrespect to the compound of formulae XVII or (XVIIp).

As an example, compounds of formulae (XXVII), (XXVIIp), (XVp) and (XV)can have the structures and stereochemistry shown below:

In some embodiments, a compound of formula (XV) can be synthesized byperforming a lactonization reaction on a compound of formula (XXVII)with the proviso that if the compounds of formulae (XXVII) and (XV) havethe same structures and stereochemistry as the compounds of formulae(XXVII-1A) and (XV-1A), then R₅ cannot be —C(═O)OR₆, wherein R₆ ishydrogen. In other embodiments, the lactonization reaction includes thefurther proviso that R₆ cannot be methyl or t-butyl when the compoundsof formulae (XXVII) and (XV) have the structures and stereochemistry ofthe compounds of formulae (XXVII-1A) and (XV-1A). In some embodiments, acompound of formula (XV) can be synthesized by performing alactonization reaction on a compound of formula (XXVII) and/or (XXVII-A)with the proviso that if R₅ is —C(═O)OR₆, wherein R₆ is hydrogen, methylor t-butyl then R₄ cannot be isopropyl. In an embodiment, a compound offormula (XV) can have the structure shown herein with the proviso thatif the compound of formula (XV) has the structure and stereochemistry ofthe compound of formula (XV-A) and R₃ is methyl then R₄ cannot be2-cyclohexenyl. In an embodiment, a compound of formula (XV) can havethe structure shown herein with the proviso that if the compound offormula (XV) has the structure and stereochemistry of the compound offormula (XV-A) and R₃ is methyl then R₄ cannot be isopropyl. In anembodiment, a compound of formula (XVp) can have the structure shownherein with the proviso that if R₃ is methyl and R₄ is isopropyl thenPG₂ cannot be DMIPS or TBS. In some embodiments, a compound of formula(XVp) can have the structure shown herein with the proviso that if thecompound of formula (XVp) has the structure and stereochemistry of thecompound of formula (XVp-A) and R₃ is methyl and R₄ is isopropyl thenPG₂ cannot be DMIPS or TBS.

In an embodiment, a compound of formula (XXVII) can have the structureshown herein with the proviso that if the compound of formula (XXVII)has the structure and stereochemistry of the compound of formula(XXVII-A), R₃ is methyl, and R₅ is —C(═O)OR₆, wherein R₆ is methyl, H ort-butyl, then R₄ cannot be 2-cyclohexenyl. In one embodiment, a compoundof formula (XXVIIp) can have the structure shown herein with the provisothat if the compound of formula (XXVIIp) has the structure andstereochemistry of the compound of formula (XXVIIp-A); R₃ is methyl; R₅is —C(═O)OR₆, wherein R₆ is hydrogen or methyl; and PG₂ is TBS or DMIPSthen R₄ cannot be isopropyl.

Other exemplary structures and stereochemistry of compounds of formulae(XXVII), (XXVIIp), (XVp) and (XV) are as follows:

As shown in Scheme 7-6, a compound of formula (XV) can further betransformed by replacing the C-13 primary hydroxy group of the compoundof formula (XV) to form a compound of formula (XVI), wherein R₃ and R₄can be the same as described with respect to the compound of formula (X)and X can be a halogen (e.g., F, Cl, Br, and I). If desired ornecessary, R₄, in some embodiments, can be protected and/or deprotectedone or several times in any of the synthetic steps described herein.

Examples of the structures and stereochemistry of compounds of formulae(XV) and (XVI) are shown below:

Further examples of the structures and stereochemistry of the compoundsof formula (XV) and (XVI) are shown below:

In one embodiment, Salinosporamide A can be synthesized by chlorinatinga compound of formula (XV), wherein R₄ is 2-cyclohexenyl and R₃ ismethyl.

In some embodiments, a compound of formula (XVI) can be prepared bysubstituting the C-13 primary hydroxy group of the compound of formula(XV), with the proviso that the compounds of formula (XV) and (XVI)cannot be the compounds of formula (XV-1A) and (XVI-1A). In certainembodiments, if the compound of formula (XVI) has the structure andstereochemistry of the compound of formula (XVI-A), then R₄ cannot beisopropyl or 2-cyclohexenyl when R₃ is methyl and X is chlorine.

In an embodiment, the C-13 primary hydroxy group of the compound offormula (XV) can be converted to a leaving group, as shown in Scheme7-7. A non-limiting list of suitable leaving groups (LG) includessulfonate leaving groups (e.g. tosylate, (OTs), mesylate (OMs), triflate(OTO, tripsylate (OTps), and mesitylate (OMst)). In an embodiment, R₃and R₄ can be the same as described with respect to the compound offormula (X). If desired, the C-5 secondary hydroxy can be protected oroxidized before converting the C-13 secondary hydroxy group of thecompound of formula (XV). After the leaving group has been added, theC-5 center can be deprotected and/or reduced to a hydroxy group.

Examples of the structures and stereochemistry of compounds of formulae(XV) and (XXXX) with a leaving group attached to the C-13 oxygen areshown below:

The leaving group of compounds of formula (XXXX) can be displaced with anucleophile (Nu) using methods known to those skilled in the art to forma compound of formula (XXXXI). See Scheme 7-8. In an embodiment, R₃ andR₄ can be the same as described with respect to the compound of formula(XXXX). Suitable nucleophiles include but are not limited to R₉S⁻, CN⁻,R₉O⁻, halide anion, NR_(9a)R_(9b) ⁻, N₃ ⁻, —CO₂R₉, R₉OH, and R₉SHwherein R₉, R_(9a) and R_(9b) can each be independently selected fromthe group consisting of hydrogen, or substituted or unsubstitutedvariants of the following: C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl,C₃-C₁₂ cycloalkyl, C₃-C₁₂ cycloalkenyl, C₃-C₁₂ cycloalkynyl, C₃-C₁₂heterocyclyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl,(cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl, and alkyl acyl, whereinR_(9a) and R_(9b) can be taken together to form an optionallysubstituted cycloalkyl.

Exemplary structures and stereochemistry of compounds of formulae (XXXX)and (XXXXI) include:

In some embodiments, the C-13 primary hydroxy group of the compound offormula (XV) can be oxidized. For example, in one embodiment, the C-13primary hydroxy group can be oxidized to an aldehyde to form a compoundof formula (XXX). See Scheme 7-9. In an embodiment, R₃ and R₄ of acompound of formula (XXX) can be the same as described with respect tothe compound of formula (XVII). If desired, the C-5 secondary hydroxycan be protected or remained unprotected during the oxidation.

Exemplary structures and stereochemistry of compounds of formulae (XV)and (XXX) are shown below:

Additional examples of the structures and stereochemistry of compoundsof formulae (XV) and (XXX) include the following:

A compound of formula (XXX) can further be transformed as shown in step(n) of Scheme 7-10. In one embodiment, a Wittig reaction can be used toconvert a compound of formula (XXX) to compounds of formulae (XXXI),wherein R₃ and R₄ can be the same as described with respect to thecompound of formula (XXX), R′ can be hydrogen, halogen, —C(═O)R″,—C(═O)OR″, —C(═O)N(R″)₂, —C(═O)SR″, —CN, —(CH₂)_(n)OH, and —(CH₂)_(n)X;R″ can be a hydrogen or a substituted or unsubstituted variant of thefollowing: alkyl, alkenyl, alkoxy, aryloxy, and arylalkoxy, and whenmore than one R″ is present, they may be the same or different; X can bea halogen; and n can be 0, 1, 2, 3, or 4. Appropriate conditions andreagents are known to those skilled in the art and include Wittigreagents such as triphenyl phosphonium ylides). In an embodiment, n canbe 0. In another embodiment, n can be 1. In still another embodiment, ncan be 2. In yet still another embodiment, n can be 3. In an embodiment,n can be 4.

Examples of the structures and stereochemistry of compounds of formulae(XXX), and (XXXI) are shown below:

Selective hydrogenation of the side chain double bond of compound offormula (XXXI) can form a compound of formula (XXXIII), as shown in step(o) of Scheme 7-10. In an embodiment, R₃, R₄ and R′ of a compound offormula (XXXIII) can be the same as described with respect to thecompound of formula (XXXI). In some embodiments, a compound of formula(XXXIII) can have the structure shown herein with the proviso that if R₃is methyl and R′ is hydrogen or chlorine then R₄ cannot be isopropyl,cyclohexyl, or phenyl.

Exemplary structures and stereochemistry of compounds of formulae(XXXI), and (XXXIII) are shown below:

In certain embodiments, compounds of formulae (XXXI) and (XXXIII) canhave the following structures and stereochemistry:

In another embodiment, nonselective reduction of the compound of formula(XXX1-A) or (XXX1-B) can be used to obtain the compounds of formulae(XXXII), respectively. In some embodiments, a compound of formula(XXXII) can have the structure shown herein with the proviso that R′cannot be hydrogen or chlorine.

A compound of formula (XXX) can also be used to form a compound offormula (XXXIV) using an organometallic reagent as shown in step (p) ofScheme 7-10. Suitable organometallic reagents include but are notlimited to organolithium compounds, organotin compounds, organocupratescompounds, organozinc, and organopalladium compounds, metal carbonyls,metallocenes, carbine complexes, and organometalloids (e.g.,organoboranes and organosilanes). In some embodiments, theorganometallic moiety can be selected from the group consisting ofR₈—MgR₇, R₈—ZnR₇, R₈—Li, (R₈)_(p)—B(R₇)_(3-p), and(R₈)_(q)—Sn(R₇)_(4-q); wherein R₇ can selected from the group consistingof halogen, or substituted or unsubstituted variants of the following:alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, isopinocampheyl, hydroxy,alkoxy, and carbonylalkoxy, wherein if more than one R₇ is present, theR₇ groups can optionally be bond together to form an optionallysubstituted cycloalkyl (e.g., 9-BBN), optionally substitutedcycloalkenyl, optionally substituted heteroalkyl or optionallysubstituted heteroalkenyl ring; p can be an integer from 1 to 3; and qcan be an integer from 1 to 4 and R₈ can selected from the groupconsisting of substituted or unsubstituted variants of the following:alkyl, alkenyl, cycloalkyl, aryl, arylalkyl. In an embodiment, theorganometallic moiety is (R₈)_(p)—B(R₇)_(3-p). In certain embodiments,the organometallic moiety is (R₈)_(p)—B(R₇)_(3-p), wherein R₈ is—(CH₂)_(a)OH. In some embodiments, the organometallic moiety is(R₈)_(p)—B(R₇)_(3-p), wherein R₈ is —(CH₂)_(a)OH, p is 1, and the two R₇groups are taken together to form an optionally substituted cycloalkyl.In another embodiment, the organometallic moiety is R₈—MgR₇. In certainembodiments, the organometallic moiety is R₈—MgR₇, wherein R₈ is—(CH₂)_(a)OH. In some embodiments, the organometallic moiety is R₈—MgR₇,wherein R₈ is —(CH₂)_(a)OH and R₇ is a halogen (e.g., chlorine). In someembodiments, R₃ and R₄ of a compound of formula (XXXIV) can be the sameas described with respect to the compound of formula (XXVI). In anembodiment, a can be 1. In another embodiment, a can be 2. In stillanother embodiment, a can be 3. In yet still another embodiment, a canbe 4. In an embodiment, a can be 5. In an embodiment, a can be 6. Instill another embodiment, In an embodiment, a can be ≧7

Examples of the structures and stereochemistry of compounds of formulae(XXX) and (XXXIV) are shown below:

In certain embodiments, R₈ can be —(CH₂)_(a)OH, wherein a can beselected from the group consisting of 1, 2, 3, 4, 6, or 7. Examples ofthe structures and stereochemistry of compounds of formulae (XXXIV-1B)when R₈ is —(CH₂)_(a)OH is shown below:

When R₈ is —(CH₂)_(a)OH, a compound of formula (XXXIV) can behalogenated to form a compound of formula (XXXV), wherein X is a halogen(e.g., F, Cl, Br, and I), as shown in Scheme 7-11. In some embodiments,R₃ and R₄ of a compound of formula (XXXV) can be the same as describedwith respect to the compound of formula (XXVI). In an embodiment, a canbe 1. In another embodiment, a can be 2. In still another embodiment, acan be 3. In yet still another embodiment, a can be 4. In an embodiment,a can be 5. In another embodiment, a can be 6. In still anotherembodiment, a can be 6. In yet still another embodiment, a can be ≧7.

Examples of the structures and stereochemistry of compounds of formulae(XXXXII) and (XXXV) are shown below:

The stereochemistry of the secondary hydroxy group of the compound offormula (XVI-B) can be inverted (e.g., by a Mitsunobu transformation) toform a compound of formula (XVI-A).

In one embodiment, Salinosporamide A can be synthesized from a compoundwith the structure and stereochemistry of formula (XVI-1B) as shownbelow:

Alternatively, the stereochemistry of the C-5 secondary hydroxy can beinverted via a multistep process, for example, by oxidizing thesecondary hydroxy to a ketone and then reducing the ketone to asecondary hydroxy of opposite stereochemistry. In one method, thecompound of formula (XVI-B) can be oxidized with a suitable oxidizingagent (e.g., Dess-Martin periodinane, TPAP/NMO, Swern oxidation reagent,PCC, or PDC) to form the compound of formula (XXII). In some embodimentsof the compound of formula (XXII), R₄ cannot be substituted orunsubstituted cyclohexenyl, unsubstituted cyclohexa-1,3-dienyl, TMSOsubstituted cyclohexa-1,3-dienyl, unsubstituted phenyl, TMSO substitutedphenyl, when R₃ is methyl and X is halogen. In an embodiment, if thecompound of formula (XXII) has the structure and stereochemistry of thecompound of formula (XXII-A), then R₄ cannot be substituted orunsubstituted cyclohexenyl, unsubstituted cyclohexa-1,3-dienyl, TMSOsubstituted cyclohexa-1,3-dienyl, unsubstituted phenyl, TMSO substitutedphenyl, when R₃ is methyl and X is halogen. The compound of formula(XXII) can then be reduced to a compound of formula (XVI-A) using asuitable chemical reagent such as sodium borohydride. In someembodiments, the reduction can be accomplished via selective enzymatictransformation. In certain embodiments, the reducing enzyme is aketoreductase such as KRED-EXP-C1A and/or KRED-EXP-B1Y.

In another embodiment, Salinosporamide A can be synthesized from acompound with the structure and stereochemistry of formula (XVI-1B) asfollows:

Moreover, the stereochemistry of the C-5 secondary hydroxy can beinverted at any time after the addition of the R₄ group to the compoundof formula (X). For example, the stereochemistry of the C-5 secondaryhydroxy can be inverted in the compounds of formulae (X), (Xp), (XI),(XIp), (XII), (XIIp), (XIII), (XIV), (XV), (XXIII), (XXIV), (XXIVp),(XXV), (XXVp), (XXVI), (XXVIp), (XXII), (XXVIII), and (XXVIIIp) In anembodiment, the stereochemistry of the C-5 secondary hydroxy can beinverted in a one step process as described herein (e.g., by a Mitsunobutransformation). The inversion can also take place in multistep process.In an embodiment, the C-5 secondary hydroxy group can be oxidized usingan appropriate oxidizing agent (e.g., Dess-Martin periodinane, TPAP/NMO,Swern oxidation reagent, PCC, or PDC) to a keto group and then reducedto a hydroxy group using a suitable reducing agent such as sodiumborohydride. In another embodiment, the keto group can be reduced viaselective enzymatic transformation. In certain embodiments, the reducingenzyme is a ketoreductase such as KRED-EXP-C1A and/or KRED-EXP-B1Y.

An alternative method for synthesizing Salinosporamide A and its analogsfrom the compound of formula (V) can proceed through a compound offormula (XVII). Scheme 8-1 shows a method of synthesizing a compound offormula (XVII) from a compound of formula (V). Scheme 8-2 shows a methodof synthesizing a compound of formula (XVII) from a compound of formula(X). Schemes 9-1 and 9-2 show methods of synthesizing Salinosporamide Aand its analogs from a compound of formula (XVII).

For some of the embodiments described herein, steps (d) and (e) ofScheme 8-1 can be the same as described above with respect to Scheme 6.

In step (f₂) of Scheme 8-1, R₄ can be added to a compound of formula(VII) using an organometallic moiety containing at least one R₄ to forma compound of formula (XVII), wherein R₁ can be hydrogen orunsubstituted or substituted C₁₋₆ alkyl; R₂ can be a hydrogensubstituted or unsubstituted variants of the following: C₁₋₆ alkyl, arylor arylalkyl; R₃ can be a substituted or unsubstituted variants of thefollowing: C₁₋₆ alkyl, a C₃₋₆ cycloalkyl, a C₂₋₆ alkenyl, C₃₋₆cycloalkenyl, aryl, or arylalkyl; PG₁ can be a protecting group moiety;and R₄ can be selected from the group consisting of substituted orunsubstituted variants of the following: C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl,C₂-C₁₂ alkynyl, C₃-C₁₂ cycloalkyl, C₃-C₁₂ cycloalkenyl, C₃-C₁₂cycloalkynyl, C₃-C₁₂ heterocyclyl, aryl, heteroaryl, arylalkyl,heteroarylalkyl, (cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl,acylalkyl, alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido,azidoalkyl, aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt ofcarboxyalkyl, alkylaminoalkyl, salt of an alkylaminoalkyl,dialkylaminoalkyl, salt of a dialkylaminoalkyl, phenyl, alkylthioalkyl,arylthioalkyl, carboxy, cyano, alkanesulfonylalkyl, alkanesulfinylalkyl,alkoxysulfinylalkyl, thiocyanoalkyl, boronic acidalkyl, boronicesteralkyl, guanidinoalkyl, salt of a guanidinoalkyl, sulfoalkyl, saltof a sulfoalkyl, alkoxysulfonylalkyl, sulfooxyalkyl, salt of asulfooxyalkyl, alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of aphosphonooxyalkyl, (alkylphosphooxy)alkyl, phosphorylalkyl, salt of aphosphorylalkyl, (alkylphosphoryl)alkyl, pyridinylalkyl, salt of apyridinylalkyl, salt of a heteroarylalkyl and halogenated alkylincluding polyhalogenated alkyl. In some embodiments, R₄ can be selectedfrom the group consisting of: substituted or unsubstituted variants ofthe following: C₃-C₁₂ heterocyclyl, aryl, heteroaryl, heteroarylalkyl,(cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl, acylalkyl,alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido, azidoalkyl,aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of a carboxyalkyl,alkylaminoalkyl, salt of an alkylaminoalkyl, dialkylaminoalkyl, salt ofa dialkylaminoalkyl, phenyl, alkylthioalkyl, arylthioalkyl, carboxy,cyano, alkanesulfonylalkyl, alkanesulfinylalkyl, alkoxysulfinylalkyl,thiocyanoalkyl, boronic acidalkyl, boronic esteralkyl, guanidinoalkyl,salt of guanidinoalkyl, sulfoalkyl, salt of a sulfoalkyl,alkoxysulfonylalkyl, sulfooxyalkyl, salt of a sulfooxyalkyl,alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of a phosphonooxyalkyl,(alkylphosphooxy)alkyl, phosphorylalkyl, salt of a phosphorylalkyl,(alkylphosphoryl)alkyl, pyridinylalkyl, salt of a pyridinylalkyl, saltof a heteroarylalkyl and halogenated alkyl including polyhalogenatedalkyl. Suitable organometallic moieties are described herein.

Exemplary structures and stereochemistry of compounds of formulae (VII)and (XVII) are shown below:

Examples of the structures of compounds of formulae (VII) and (XVII) areshown below:

A compound of formula (XVII) can also be synthesized from a compound offormula (X) by oxidizing the secondary alcohol group of the compound offormula (X), according to Scheme 8-2. The compound of formula (X) can besynthesized as described in Scheme 6.

Exemplary structures of compounds of formula (X) and (XVII) are asfollows:

Additionally, a compound of formula (XVII) can be obtained via thesynthetic Scheme 8-3.

A compound of formula (VII) can be synthesized from a compound offormula (V) via steps (d) and (e) of Scheme 8-3 that are described abovewith respect to Scheme 6. The ester of the compound of formula (VII) canbe transformed to a carboxylic acid using methods known to those skilledin the art (e.g., hydrolysis by LiOH, alkaline thioates such as LiSMe,NaSMe, LiSC₂H₅, etc.) which can be further transformed to acid halideusing a suitable reagent (e.g. Oxalyl chloride, SOCl₂ etc.) to form acompound of formula (XXXVI). In an embodiment, R₁, R₃ and PG₁ of thecompound of formula (XXXVI) can be the same as described with respect tothe compound of formula (VII) and X is a halogen.

Examples of the structures of compounds of formula (VII) and (XXXVI) areshown below:

The carboxylic acid/acid halide of the compound of formula (XXXVI) canbe reacted with an appropriate N,O-dimethylhydroxylamine hydrochloride[HCl.HNMe(OMe)] to form the corresponding Weinreb amide, wherein R₁, R₃and PG₁ can be the same as described with respect to the compound offormula (VII) and R′″ and R″″ can each independently be selected fromthe group consisting of alkyl (e.g. methyl), alkoxy (e.g. methoxy).

Exemplary structures of compounds of formula (XXXVI) and (XXXVII) are asfollows:

The Weinreb amide of the compound of formula (XXXVII) can be reactedwith an appropriate organometallic moiety containing at least one R₄ toform a compound of formula (XVII). In an embodiment, R₁, R₃ and PG₁ canbe the same as described with respect to the compound of formula (VII)and R₄ can be selected from the group consisting of substituted orunsubstituted variants of the following: C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl,C₂-C₁₂ alkynyl, C₃-C₁₂ cycloalkyl, C₃-C₁₂ cycloalkenyl, C₃-C₁₂cycloalkynyl, C₃-C₁₂ heterocyclyl, aryl, heteroaryl, arylalkyl,heteroarylalkyl, (cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl,acylalkyl, alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido,azidoalkyl, aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt ofcarboxyalkyl, alkylaminoalkyl, salt of an alkylaminoalkyl,dialkylaminoalkyl, salt of a dialkylaminoalkyl, phenyl, alkylthioalkyl,arylthioalkyl, carboxy, cyano, alkanesulfonylalkyl, alkanesulfinylalkyl,alkoxysulfinylalkyl, thiocyanoalkyl, boronic acidalkyl, boronicesteralkyl, guanidinoalkyl, salt of a guanidinoalkyl, sulfoalkyl, saltof a sulfoalkyl, alkoxysulfonylalkyl, sulfooxyalkyl, salt of asulfooxyalkyl, alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of aphosphonooxyalkyl, (alkylphosphooxy)alkyl, phosphorylalkyl, salt of aphosphorylalkyl, (alkylphosphoryl)alkyl, pyridinylalkyl, salt of apyridinylalkyl, salt of a heteroarylalkyl and halogenated alkylincluding polyhalogenated alkyl. In some embodiments, R₄ can be selectedfrom the group consisting of: substituted or unsubstituted variants ofthe following: C₃-C₁₂ heterocyclyl, aryl, heteroaryl, heteroarylalkyl,(cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl, acylalkyl,alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido, azidoalkyl,aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of a carboxyalkyl,alkylaminoalkyl, salt of an alkylaminoalkyl, dialkylaminoalkyl, salt ofa dialkylaminoalkyl, phenyl, alkylthioalkyl, arylthioalkyl, carboxy,cyano, alkanesulfonylalkyl, alkanesulfinylalkyl, alkoxysulfinylalkyl,thiocyanoalkyl, boronic acidalkyl, boronic esteralkyl, guanidinoalkyl,salt of guanidinoalkyl, sulfoalkyl, salt of a sulfoalkyl,alkoxysulfonylalkyl, sulfooxyalkyl, salt of a sulfooxyalkyl,alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of a phosphonooxyalkyl,(alkylphosphooxy)alkyl, phosphorylalkyl, salt of a phosphorylalkyl,(alkylphosphoryl)alkyl, pyridinylalkyl, salt of a pyridinylalkyl, saltof a heteroarylalkyl and halogenated alkyl including polyhalogenatedalkyl. Suitable organometallic moieties are described herein.

In certain embodiments, compounds of formulae (XXXVII) and (XVII) canhave the following structures and stereochemistry:

One method for obtaining Salinosporamide A and analogs thereof from acompound of formula (XVII) is shown in Scheme 9-1:

As shown in step (g₂) of Scheme 9-1, the aminal of a compound of formula(XVII) can be cleaved to form a compound of formula (XVIII) using anacid reagent (e.g., triflic acid or HCl). In some embodiments, R₁, R₃,R₄ and PG₁ of a compound of formula (XVIII) can be the same as describedwith respect to the compound of formula (XVII).

As an example, the compounds of formula (XVII) and (XVIII) may have thefollowing structures and stereochemistry:

Exemplary structures of compounds of formula (XVII) and (XVIII) areshown below:

In step (h₂), the C-15 primary alcohol group of a compound of formula(XVIII) can be converted to R₅, which can be selected from the groupconsisting of —C(═O)OR₆, —C(═O)SR₆, —C(═O)NR₆R₆ and —C(═O)Z, whereineach R₆ can be independently selected from the group consisting ofhydrogen, halogen, or substituted or unsubstituted variants of thefollowing: C₁-C₂₄ alkyl, acyl, alkylacyl, arylacyl, aryl, arylalkyl,p-nitrophenyl, pentafluorophenyl, pentafluoroethyl, trifluoroethyl,trichloroethyl, and heteroaryl; and Z can be a halogen. The conversionof the primary alcohol group to R₅ may be achieved by converting thealcohol group to a carboxylic acid (R₆═H) using an appropriate oxidationconditions such as Jones oxidation. Alternatively the carboxylic acidgroup can be prepared from the primary alcohol group of the compound offormula (XVIII) through an aldehyde. The primary alcohol group of thecompound of formula (XVIII) can first be converted to aldehyde usingappropriate oxidant such as Des s-Martin periodinane, TPAP, Swernoxidation reagent, PCC, or PDC and then the resulting aldehyde can beoxidized further to carboxylic acid using appropriate oxidants such as acombination of sodium chlorite/sodium phosphatedibasic/2-methyl-2-butene. If desired the carboxylic acid can then beconverted to an ester, a thioester, or an anhydride to form a compoundof formula (XIX) using an appropriate alcohol, thiol (e.g. thiophenol,cystine), carboxylic acid (e.g. acetic acid, benzoic acid), or anhydride(e.g. acetic anhydride). In some embodiments, R₃ and R₄ of a compound offormula (XIX) can be the same as described with respect to the compoundof formula (XVIII).

Compounds of formula (XVIII) and (XIX) may have the following structuresand stereochemistry:

For example the compounds of formula (XVIII) and (XIX) may have thefollowing structures:

In step (i₂) of Scheme 9-1, a compound of formula (XX) can besynthesized by removing the protecting group moiety on the compound offormula (XIX) and reductively opening the resulting hemiacetal. As anexample, the hemiacetal can be reductively opened using a reducing agent(e.g., sodium borohydride). In some embodiments, R₃, R₄, and R₅ of acompound of formula (XX) can be the same as described with respect tothe compound of formula (XIX).

Exemplary structures and stereochemistry of compounds of formula (XIX)and (XX) can be as follows:

For example, compounds of formula (XIX) and (XX) can have the followingstructures:

Using an appropriate base (e.g. BOPCl/pyridine), a compound of formula(XXI) can be synthesized from a compound of formula (XX) via alactonization reaction, as shown in step (j₂) of Scheme 9-1. In anembodiment, R₃, R₄, and R₅ of a compound of formula (XXI) can be thesame as described with respect to the compound of formula (XX).

Examples of the structures and stereochemistry of compounds of formula(XX) and (XXI) are shown below:

For example, compounds of formula (XX) and (XXI) can have the followingstructures:

As shown in step (k₂) of Scheme 9-1, a compound of formula (XXI) canfurther be transformed by substituting the primary hydroxy of thecompound of formula (XXI) to form a compound of formula (XXII). In someembodiments, R₃ and R₄ of a compound of formula (XXII) can be the sameas described with respect to the compound of formula (XXI), and X can bea halogen.

Exemplary structures and stereochemistry of compounds of formula (XXI)and (XXII) are shown below:

For example, compounds of formula (XXI) and (XXII) can have thefollowing structures:

As shown step (l₂) of Scheme 9-1, the C-5 ketone group attached to thecarbon adjacent to R₄ of a compound of formula (XXII) can be reduced toa secondary hydroxy group using a suitable reducing agent (e.g., sodiumborohydride) or an enzyme to form a compound of formula (XVI). In oneembodiment, the compound of formula (XXII) can be reduced to thecompound of formula (XVI-A) and/or (XVI-B).

Examples of the structures and stereochemistry of compounds of formula(XXII) and (XVI) are shown below:

As another example, the compounds of formula (XXII) and (XVI) may havethe following structures and stereochemistry:

If desired, the stereochemistry of the secondary hydroxy of the compoundof formula (XVI-B) can be inverted in a single step or a multistepprocess, as described herein.

A compound of formula (XXI) can also be used to synthesize a compound offormula (XV), as shown in Scheme 9-1. The C-5 keto group of the compoundof formula (XXI) can be reduced using an appropriate reducing agent suchas those described herein to form a compound of formula (XV). The C-13primary hydroxy of the compound of formula (XV) can be used to obtainSalinosporamide A or analogs thereof following Schemes 7-6, 7-7, 7-8,7-9, 7-10 and 7-11 described herein. The stereochemistry of thesecondary hydroxy of the compound of formula (XVI-B) can be inverted ina single step or a multistep process, such as those described.

In certain embodiments, the compounds of formulae (XXI), (XV), and (XVI)can have the following structures and stereochemistry:

In some embodiments, compounds of formula (XV) can be synthesized viaScheme 9-2.

A compound of formula (XXI) can be synthesized from a compound offormula (XVII) via steps (g₂), (h₂), (i₂) and (j₂) of Scheme 9-2 thatare described above with respect to Scheme 9-1. The C-5 keto group ofthe compound of formula (XXI) can be reduced to a secondary hydroxygroup using a suitable reducing agent (e.g., sodium borohydride) or anenzyme to form a heterocyclic compound of formula (XV), for example,compounds (XV-A) and/or (XV-B), wherein R₃, R₄, and X can be the same asdescribed with respect to the compound of formula (XXII).

Exemplary structures and stereochemistry of the compounds (XXI) and (XV)are shown below:

The compound of formula (XV) can then be used to obtain SalinosporamideA or analogs thereof following Schemes 7-6, 7-7, 7-8, 7-9, 7-10 and 7-11described herein.

Another method for obtaining Salinosporamide A and analogs thereof froma compound of formula (XVII) is shown in Scheme 9-3.

Preceding the cleavage of the aminal, the ketone group of a compound offormula (XVII) can be protected using a suitable protecting groupmoiety/moieties to form a compound of formula (XVIIp). In someembodiments, R₁, R₃, R₄, and PG₁ can be the same as described withrespect to the compound of formula (XVII), each Y can be an oxygen orsulfur, and R_(A) and R_(B) can be each independently selected from thegroup consisting of C₁₋₆ alkyl, C₂₋₆ alkenyl and C₂₋₆ alkynyl, whereinR_(A) and R_(B) can be optionally bound together to form an optionallysubstituted 5, 6, 7, or 8 membered heterocyclyl.

As shown in Scheme 9-3, a compound of formula (XVIIp) can be transformedto a compound of formula (XXIIp) following the methods as described withrespect to steps (g₂), (h₂), (i₂), (j₂), and (k₂) of Scheme 9-1. Asshown in Scheme 9-3, the protecting group moiety/moieties, Y-R_(A) andY-R_(B), can be removed from a compound of formula (XXIIp) using asuitable method to obtain a compound of formula (XXII). For each step,the substituents of the ketone protected compounds can be selected fromthe same groups as those described with respect to the correspondingunprotected compounds. For example, R₃, R₄, PG₁ and R₅ of a compound offormula (XIXp) can be selected from the same groups as a compound offormula (XIX). In some embodiments, the compounds of formula (XVIIp),(XVIIIp), (XIXp), (XXp), (XXIp) and (XXIIp), can have the samestructures and/or stereochemistry as the corresponding non-protectedcompounds of Scheme 9-1 except that the keto carbonyl group is protectedwith a suitable protecting group(s).

Finally, the ketone group attached to the carbon adjacent to R₄ of acompound of formula (XXII) can be reduced to a hydroxy group using asuitable reducing agent (e.g., sodium borohydride) or an enzyme to forma compound of formula (XVI), including (XVI-A) and/or (XVI-B), whereinR₃, R₄, and X can be the same as described with respect to the compoundof formula (XXII).

In an embodiment, compounds of formula (XV) can be synthesized from acompound of formula (XVII) is shown in Scheme 9-4.

A compound of formula (XXIp) can be synthesized from a compound offormula (XVII) via steps (g₂), (h₂), (i₂) and (j₂) of Scheme 9-4 thatare described above with respect to Scheme 9-1. The protecting groupmoiety/moieties, Y-R_(A) and Y-R_(B), can be removed from a compound offormula (XXIp) using a suitable method to obtain a compound of formula(XXI). In an embodiment, R₃ and R₄ can be the same as described withrespect to the compound of formula (XVII). The C-5 keto group of thecompound of formula (XXI) can be reduced to a secondary hydroxy groupusing a suitable reducing agent (e.g., sodium borohydride) or an enzymeto form a compound of formula (XV), including (XV-A) and/or (XV-B),wherein R₃ and R₄ can be the same as described with respect to thecompound of formula (XXII). The compound of formula (XV) can then beused to obtain Salinosporamide A or analogs thereof following Schemes7-6, 7-7, 7-8, 7-9, 7-10, and 7-11 described herein.

In certain embodiments, the compounds of formulae (XXIp), (XXI), and(XV) can have the following structures and stereochemistry:

Additional methods for synthesizing Salinosporamide A and analogsthereof are shown below in Schemes 9-5 and 9-6. The PG₁ of the compoundof formula (XVII) or (XVIIp) can be removed and the resulting hemiacetalcan be reductively opened as described above to form compounds offormulae (XXXVIII) and (XXXVIIIp), respectively. The aminal of thecompounds of formulae (XXXVIII) and (XXXVIIIp) can be cleaved asdescribed herein to form compounds of formula (XXXIX) and (XXXIXp),respectively. The C-15 primary alcohol group of the compounds of formula(XXXIX) and (XXXIXp) can be converted to R₅ using the methods describedherein, wherein R₅ which can be selected from the group consisting of—C(═O)OR₆, —C(═O)SR₆, —C(═O)NR₆R₆ and —C(═O)Z, each R₆ can beindependently selected from the group consisting of hydrogen, halogen,or substituted or unsubstituted variants of the following: each R₆ canbe independently selected from the group consisting of hydrogen,halogen, or substituted or unsubstituted variants of the following:C₁-C₂₄ alkyl, acyl, alkylacyl, arylacyl, aryl, arylalkyl, p-nitrophenyl,pentafluorophenyl, pentafluoroethyl, trifluoroethyl, trichloroethyl, andheteroaryl, and Z can be a halogen. After the transformation of R₅, acompound of formula (XVI) can be formed as described above with respectto Schemes 9-1 and 9-3. If desired, the C-13 primary hydroxy group canbe protected during the oxidation of C-15 hydroxy group of compounds offormulae (XXXIX) and (XXXIXp) and then removed if desired.

Additional methods of synthesizing compounds of formula (XV) are shownin Schemes 9-7 and 9-8. The PG₁ of the compound of formula (XVII) or(XVIIp) can be removed and the resulting hemiacetal can be reductivelyopened as described above to form compounds of formulae (XXXVIII) and(XXXVIIIp), respectively. The aminal of the compounds of formulae(XXXVIII) and (XXXVIIIp) can be cleaved as described herein to formcompounds of formula (XXXIX) and (XXXIXp), respectively. The C-15primary alcohol group of the compounds of formula (XXXIX) and (XXXIXp)can be converted to R₅ using the methods described herein, wherein R₅which can be selected from the group consisting of —C(═O)OR₆, —C(═O)SR₆,—C(═O)NR₆R₆—C(═O)Z; each R₆ can be independently selected from the groupconsisting of hydrogen, halogen, or substituted or unsubstitutedvariants of the following: C₁-C₂₄ alkyl, acyl, alkylacyl, arylacyl,aryl, arylalkyl, p-nitrophenyl, pentafluorophenyl, pentafluoroethyl,trifluoroethyl, trichloroethyl, and heteroaryl, and Z can be a halogen.After the transformation of R₅, a compound of formula (XVI) can beformed as described above with respect to Schemes 9-1, 9-2, 9-3, and9-4. A compound of formula (XV) obtained via the methods of Schemes 9-7and/or 9-8 can then used to synthesize Salinosporamide A or analogsthereof following Schemes 7-6, 7-7, 7-8, 7-9, 7-10, and 7-11 asdescribed herein.

Examples of the structures and stereochemistry of the compounds offormulae (XXXVIII) and (XXXIX) (XXXIXp) are shown below:

In some embodiments, the compounds of formula (XXXVIIIp) and (XXXIXp)can have the same structures and/or stereochemistry as the correspondingnon-protected compounds of formulae (XXXVIII) and (XXXIX) except thatthe keto carbonyl group is protected with a suitable protectinggroup(s).

In one embodiment, Salinosporamide A (compound XVI-1A) can be obtainedfrom a compound of formula (XXII), wherein R₄ is 2-cyclohexenyl, R₃ ismethyl and X is chlorine.

In another embodiment, the compound of formula (XXII-1) can be convertedto a compound of formula (XVI-B). If desired, the stereochemistry of theC-5 secondary hydroxy of the compound of formula (XVI-B) can be invertedin a single step or a multistep process to give a compound of formula(XVI-A), as previously described herein.

Salinosporamide A or analogs thereof can also be obtained from thecompound of formula (XXI) and/or (XXIp). In an embodiment, the C-13primary hydroxy of the compounds of formulae (XXI) and (XXIp) can bemodified following the procedures shown in Schemes 7-6, 7-7, 7-8, 7-9,7-10, and 7-11 described herein. Reduction of the C-5 keto group to ahydroxy group using an appropriate reducing agent (e.g., sodiumborohydride) to produce Salinosporamide A or analogs thereof can takeplace at any step shown in Schemes 7-6, 7-7, 7-8, 7-9, 7-10, and 7-11.

The stereochemistry of the C-5 secondary hydroxy can be inverted at anytime using one of the methods described herein or one known to thoseskilled in the art. For example, the stereochemistry of the C-5secondary hydroxy can be inverted in the compound of formula (XV). In anembodiment, the stereochemistry of the C-5 secondary hydroxy can beinverted in a one step process as described herein (e.g., by a Mitsunobutransformation). The inversion can also take place in multistep process.In an embodiment, the C-5 secondary hydroxy group can be oxidized usingan appropriate oxidizing agent (e.g., Dess-Martin periodinane, TPAP/NMO,Swern oxidation reagent, PCC, or PDC) to a keto group and then reducedto a hydroxy group using a suitable reducing agent such as sodiumborohydride. In another embodiment, the keto group can be reduced viaselective enzymatic transformation. In certain embodiments, the reducingenzyme is a ketoreductase such as KRED-EXP-C1A and/or KRED-EXP-B1Y.

In some embodiments, R₄ cannot be 2-cyclohexenyl in any of the compoundsand methods described herein. In other embodiments, R₄ is 2-cyclohexenylin any of the compounds and methods described herein. In someembodiments, R₄ cannot be isopropyl in any of the compounds and methodsdescribed herein. In other embodiments, R₄ is isopropyl in any of thecompounds and methods described herein.

EXAMPLES

Commercially available compounds were obtained from Sigma-Aldrich andwere used without purification unless stated. ¹H NMR, ¹³C NMR, and ¹H-¹HCOSY spectra were recorded at 500 MHz on a Bruker spectrometer andchemical shifts are given in δ-values [ppm] referenced to the residualsolvent peak chloroform (CDCl₃) at 7.24 and 77.00, respectively. TheLC-MS data were obtained from an Agilent HP1100 HPLC equipped with anAgilent PDA detector (the mobile phase was a mixture of CH₃CN and H₂O)and MSD system. The optical rotations were obtained from Autopol-IIIautomatic polarimeter and the melting point was from MeI-Temp apparatus.

Example 1 Synthesis of (I-1)

To a suspension of D-serine methylester hydrochloride (25 g, 160.67mmol) in pentane (800 mL) at room temperature were added t-butylaldehyde (20.73 g, 241 mmol) and Et₃N (17.85 g, 176.74 mmol). Thereaction mixture was refluxed for 15 hrs at 50° C. using Dean-Starkapparatus. The resulting reaction mixture was cooled to roomtemperature, filtered through celite, and the celite cake was washedwith pentane (2×40 mL). The combined filtrate was concentrated underreduced pressured and dried under high vacuum to afford product, I-1(24.5 g, 131 mmol, 81.5% yield) as clear oil, which can be used withoutfurther purification. The compound I-1 was characterized by ¹H-NMR(CDCl₃, 500 MHz). See FIG. 2.

Example 2 Synthesis of the Ester Precursor of Compound (II-1)

Method A

To a solution of t-butylacetoacetate (30 g, 0.19 mol) in dry THF (800mL) at 0° C. was added t-BuOK (23.41 g, 95% w/w, 0.21 mol) and thesolution was stirred for about 15 minutes. Allylbromide (18.39 g, 0.152mol) was added and the solution was stirred at 0° C. for additional 15min. The reaction mixture was then allowed to warm to room temperatureand stirred for about 5 hours under an atmosphere of N₂. The abovereaction mixture was then cooled to 0° C., quenched with H₂O (300 mL),and extracted with EtOAc (3×200 mL). The combined organic phase wasdried over Na₂SO₄ and concentrated under reduced pressure. The crudeproduct was purified by silica gel flash chromatography (5 cm ID×45 cm)using a solvent gradient of 100% hexanes (1.5 L) to 1.5% EtOAc/hexanes(3 L) to 2.5% EtOAc/hexanes (1 L) to 4% EtOAc/hexanes (700 mL) to affordpure product (14.5 g, 0.073 mol, 38.5% yield). Alternatively, The crudeproduct was purified by fractional distillation (130° C. oil bath,90-95° C. bp) under high vacuum (12 mm Hg) to afford product, the esterprecursor of the compound (II-1) (66% yield).

Method B

To a solution of t-BuOK (50 g, 95% w/w, 0.42 mol) in dry THF (1.5 L) at0° C. was added t-butylacetoacetate (65 g, 0.41 mol) and the solutionwas stirred for about 15 minutes under an atmosphere of N₂. Allylbromide(47 g, 0.39 mol) was added slowly and the solution was stirred at 0° C.for about 20 hours. The reaction mixture was allowed to warm to roomtemperature and stirred for additional 15 hours. The reaction mixturewas then quenched with H₂O (1 L) at 0° C. and extracted with EtOAc(3×0.5 mL). The organic phase was dried over MgSO₄ and concentratedunder reduced pressure. The crude product was purified by fractionaldistillation (130° C. oil bath, 90-95° C. bp) under high vacuum (12 mmHg) to afford the product, the ester precursor of the compound (II-1)(54 g, 0.27 mol, 66% yield). ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.68 (m, 1H),5.03 (br dd, J=1, 17 Hz, 1H), 4.97 (br dd, J=1, 10 Hz, 1H), 3.35 (t,J=7.5 1H), 2.48 (br t, J=7.0, 2H), 2.16 (s, 3H), 1.39 (s, 9H). See FIG.3.

Example 3 Synthesis of the Protected Ester Precursor of Compound (II-1)

To a solution of the ester precursor (45 g, 0.23 mol) in hexanes (1.6 L)were added ethylene glycol (70.5 g, 1.15 mol) and PPTS (2.85 g, 0.011mol). The reaction mixture was refluxed at 95° C. using Dean-Starkapparatus for 6 days (Note: 28.5 g, 0.46 mol of ethylene glycol wasadded to the reaction mixture every two days to maintain itsconcentration), then cooled to room temperature. The reaction mixturewas then neutralized with 800 μL of Et₃N and diluted with H₂O (500 mL).The organic layer was separated, dried over Na₂SO₄ and concentratedunder reduced pressure to afford product, the protected ester precursorof the compound (II-1) (44 g, 0.18 mmol, 80% yield), which can be usedfor the next step without purification. ¹H-NMR (CDCl₃, 500 MHz) (δ):5.72 (m, 1H), 5.06 (dd, J=1, 17 Hz, 1H), 4.97 (d, J=10 Hz, 1H), 3.94 (m,4H), 2.60 (dd, J=3.6, 11.5 Hz, 1H), 2.43 (m, 1H), 2.29 (m, 1H), 1.42 (s,9H), 1.38 (s, 3H). See FIG. 4.

Example 4 Synthesis of Compound (II-1)

To a solution of the ester with protecting group moieties precursor (28g, 0.115 mol) in CH₂Cl₂ (28 mL) at 0° C. was added trifluoroacetic acid(TFA neat, 56 mL, 0.727 mol) and the solution was stirred for about 5min. The reaction mixture was then allowed to warm to room temperatureand stirred for one hour. The reaction mixture was diluted with CH₂Cl₂(400 mL) and extracted with ice cold water (3×300 mL). The organic layerwas dried over Na₂SO₄, concentrated under reduced pressure and driedunder high-vacuum for about one hour (to remove the residual TFA) toafford the product, compound II-1 (15.5 g, 0.083 mol, 72% yield) aslight yellow oil, which can be used for the next step withoutpurification. The compound II-1 was characterized by ¹H-NMR (CDCl₃, 500MHz): ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.77 (m, 1H), 5.10 (br dd, J=1, 17Hz, 1H), 5.02 (br d, J=10 Hz, 1H), 4.00 (m, 4H), 2.76 (dd, J=3.8, 11.0Hz, 1H), 2.43 (m, 2H), 1.41 (s, 3H). See FIG. 5.

Example 5 Synthesis of Compound (III-1)

To a solution of compound II-1 (4.8 g, 25.81 mmol) in dry CH₂Cl₂ (200mL) at 0° C. were added Et₃N (7.82 g, 77.42 mmol) and methanesulfonylchloride (5.89 g, 51.62 mmol) and the solution was stirred for about 10min. Then compound I-1 (5.31 g, 28.4 mmol) was added, the reactionmixture was allowed to warm to room temperature slowly and stirred forabout 15 hrs. Then the reaction mixture was quenched with H₂O (200 mL)and extracted with CH₂Cl₂ (3×100 mL). The combined organic layer wasdried over Na₂SO₄ and concentrated under reduced pressure to yield amixture of two diastereomers (3:2). See FIG. 6 b. The crude product waspurified by silica flash chromatography (3 cm ID×30 cm) using a solventgradient of 19:1 (500 mL) to 9:1 (500 mL) to 17:3 (500 mL) to 4:1 (1.5L) to 3:1 (1 L) hexane/EtOAc to afford the product, compound III-1 (6 g,16.9 mmol, 65.5% yield). The compound III-1 was characterized by ¹H-NMR(CDCl₃, 500 MHz). See FIG. 6. MS (ESI) m/z 356 [M+H].

Example 6 Synthesis of Compound (IV-1)

Method A: To a solution of compound III-1 (6 g, 16.9 mmol) in CH₃CN (350mL) were added sodium iodide (3.3 g, 21.97 mmol) and cerium (III)chloride heptahydrate (9.45 g, 25.35 mmol) and the reaction mixture wasstirred at 60-65° C. for 4 hours (the reaction progress can be monitoredby LC-MS). The above reaction mixture was then quenched with water (200mL) and extracted with EtOAc (3×150 mL). The combined organic layer(cloudy) was concentrated under reduced pressure to remove all of theCH₃CN/EtOAc, leaving about 20 mL of H₂O (CH₃CN soluble part), which wasfurther extracted with EtOAc (100 mL). The organic layer was dried overNa₂SO₄, and concentrated under reduced pressure to afford the product,IV-1 (4.4 g, 14.2 mmol, 83.5% yield) as a mixture of two diasteromers(3:2). See FIG. 7 e. If desired, the product can be used for the nextstep without purification. The compound IV-1 was characterized by ¹H-NMR(CDCl₃, 500 MHz) and NOESY (CDCl₃, 500 MHz). See FIGS. 7 a and 7 b. MS(ESI) m/z 312 [M+H]. A portion of the product was further purified byreverse phase HPLC using C-18 column (150 mm×21 mm), and an isocraticsolvent system of 40% acetonitrile in H₂O at a flowrate of 14.5 mL/minto afford individual diastereomers IV-1A and IV-1B as pure samples. Thediastereomers IV-1A and IV-1B were characterized by ¹H-NMR (CDCl₃, 500MHz). See FIGS. 7 c and 7 d.

Compound IV-1A: ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.73 (m, 1H), 5.34 (s, 1H),5.12 (m, 1H), 5.05 (d, J=10.1 Hz, 1H), 4.64 (d, J=6.3 Hz, 1H), 4.53 (d,J=8.2 Hz, 1H), 3.90 (t, J=7.6 Hz, 1H), 3.80, (s, 3H), 3.67 (t, J=7.6 Hz,1H), 2.60 (m, 2H), 2.27 (s, 3H), 0.91 (s, 9H); MS (ESI) m/z 312 [M+H]⁺.

Compound IV-1B: ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.76 (m, 1H), 5.28 (s, 1H),5.18 (br d, J=17.3 Hz 1H), 5.08 (d, J=10.1 Hz, 1H), 4.88 (m, 1H), 4.52(d, J=8.2 Hz, 1H), 3.88 (m, 1H), 3.81, (m, 1H), 3.76 (s, 3H), 2.88 (m,1H), 2.63 (m, 1H), 2.21 (s, 3H), 0.86 (s, 9H); MS (ESI) m/z 312 [M+H]⁺.

Method B: A mixture of compound III-1 (175 mg, 0.493 mmol) and iodine(12.52 mg, 0.0493 mmol) in acetone (20 mL) was refluxed at 56° C. forone hour. The reaction mixture was then cooled to RT, the acetone wasremoved under reduced pressure, and the crude reaction product wasdissolved in CH₂Cl₂ (20 mL). The CH₂Cl₂ solution was washed successivelywith 5% aqueous sodium thiosulfate (10 mL), H₂O (10 mL) and brine (10mL). The resulting organic phase was dried over Na₂SO₄, concentratedunder reduced pressure and purified by silica gel plug column (2.5 cmID×6 cm) using a solvent gradient of 19:1 (50 mL) to 9:1 (100 mL) to 4:1(100 mL) to 3:1 (100 mL) to 7:3 (100 mL) hexanes/EtOAc to afford theproduct, compound IV-1 (97 mg, 0.312 mmol, 63.3% yield).

Method C: A mixture of compound III-1 (500 mg, 1.40 mmol) and LiBF₄ (200mg, 2.1 mmol) in CH₃CN (6 mL, wet with 2% H₂O) was stirred at 70° C. for1.5 to 2 hrs (the reaction progress can be monitored by LC-MS). Theabove reaction mixture was then quickly cooled to 0° C., filteredthrough a short silica plug and concentrated under reduced pressure. Theproduct was purified by silica gel column chromatography (1.25 cm ID×5cm) using a solvent gradient of 19:1 (50 mL) to 9:1 (50 mL) to 4:1 (50mL) hexanes/EtOAc to afford the purified product, compound IV-1 (260 mg,0.84 mmol, 60% yield).

Example 7 Synthesis of Compound (V-1A)

To a solution of compound IV-1 (26 g, 83.6 mmol) in dry THF (2.7 L) atRT was added t-BuOK (4.68 g, 41.8 mmol). The reaction mixture wasstirred at RT for 15 min under an atmosphere of N₂ and then quenchedwith H₂O (900 mL) and extracted with EtOAc (3×400 mL). The combinedorganic phase was washed with saturated brine solution, dried overNa₂SO₄ and concentrated under reduced pressure. The reaction mixture wasdissolved in 1:1 ether: hexanes (75 mL each) and transferred to acrystallization dish, where it was allowed to stand and crystallize.After an hour, the crystals (1^(st) crop) were separated by decantingthe mother liquor. The crystals were washed with ether (2×10 mL) andhexanes (2×10 mL). The combined mother liquor and washes wasconcentrated under reduced pressure and redissolved in 1:1 ether:hexanes(50 mL each) and the crystallization process was repeated thecrystallization process as described above. The crystals (2^(nd) crop)were separated by decanting the mother liquor. The crystals were washedwith ether (2×10 mL) and hexanes (2×10 mL). The two crops of crystalswere combined to obtain compound V-1A (13.5 g, 43.4 mmol, 51.9% yield bycrystallization). The mother liquor was chromatographed on a silica gelflash column (30×4 cm) using solvent gradient of 19:1 (500 mL) to 9:1 (1L) to 17:3 (500 mL) EtOAc/hexanes to yield the compound XXIX-1 (2.47 g),compound V-1A (3.05 g), compound V-1B (250 mg as a mixture) and compoundV-1C (1.81 g). The two crops of crystals were combined to obtain a totalyield of 63.6% of the compound V-1A. Compound V-1A was obtained as acolorless crystalline material. The structures of compounds V-1B, V-1C,and XXIX-1 are shown below.

Compound V-1A: ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.96 (m, 1H), 5.15 (br dd,J=1.5, 17.2 Hz, 1H), 5.05 (d, J=10.1 Hz, 1H), 4.93 (s, 1H), 4.50 (d,J=8.9 Hz, 1H), 4.26 (d, J=8.9 Hz, 1H), 3.77 (s, 3H), 3.10 (t, J=6.7 Hz,1H), 2.56 (m, 1H), 2.31 (m, 1H), 1.96 (s, 1H), 1.30 (s, 3H), 0.87 (s,9H). ¹³C-NMR (CDCl₃, 125 MHz) (δ): 177.9, 171.8, 136.7, 116.6, 96.7,80.4, 79.2, 68.0, 53.3, 52.6, 36.5, 27.9, 25.0 (3×CH₃), 23.0. M.P.113-114° C. (crystals obtained from 1:1; diethyl ether:hexanes). [α]²²_(D) 8.4 (c 0.96, CH₃CN). MS (ESI) m/z 312 (M+H). See FIG. 8.

The compound V-1A was also characterized by ¹³C-NMR (CDCl₃, 125 MHz) and¹H-¹H COSY NMR (CDCl₃, 500 MHz). See FIGS. 9 and 10. The structure ofcompound V-1A was confirmed by x-ray crystallography, as shown in FIG.11.

Compound V-1B: Compound V-1B was purified by reversed phase HPLC usingthe solvent gradient of 30% to 70% CH₃CN/H₂O over 30 min, at a flow rateof 14.5 mL/min to yield pure compound. ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.88(m, 1H), 5.09 (br dd, J=1.5, 17 Hz, 2H), 4.9 (s, 1H), 4.52 (d, J=9 Hz,1H), 4.2 (d, J=9 Hz, 1H), 3.77 (s, 3H), 2.68 (m, 1H), 2.51 (t, J=7 Hz,1H), 2.45 (m, 1H), 1.29 (s, 3H), 0.89 (s, 9H). See FIG. 25. MS (ESI) m/z312 [M+H]⁺. The structure was confirmed by x-ray crystallography, FIG.26.

Compound V-1C: ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.93 (m, 1H), 5.16 (br dd,J=1, 17 Hz, 1H), 5.06 (br d, J=10 Hz, 1H), 4.88 (s, 1H), 4.58 (d, J=9.5Hz, 1H), 3.96 (d, J=9.5 Hz, 1H), 3.79 (s, 3H), 3.43 (dd, J=6.3, 8.5 Hz,1H), 2.53 (m, 1H), 2.17 (m, 1H), 1.27 (s, 3H), 0.86 (s, 9H). See FIG.27. ¹³C-NMR (CDCl₃, 125 MHz) (δ): 175.8, 171.5, 135.8, 116.9, 96.2,80.9, 78.3, 68.8, 53.3, 52.6, 36.5, 28.8, 25.0, 20.2. See FIG. 28. MS(ESI) m/z 312 [M+H]⁺. The relative stereochemistry was determined byNOESY, FIG. 29.

Compound of XXIX-1: ¹H-NMR (CDCl₃, 500 MHz) (δ): 5.81 (m, 1H), 5.04 (brdd, J=1.5, 7.5 Hz, 1H), 5.02 (s, 1H), 4.78 (d, J=8.5 Hz, 1H), 4.66 (s,1H), 3.74 (s, 3H), 3.18 (d, J=8.5 Hz, 1H), 2.97 (t, J=6.5 Hz, 1H), 1.83(s, 3H), 0.91 (s, 9H). See FIG. 30. ¹³C-NMR (CDCl₃, 125 MHz) (δ): 178.4,170.0, 151.9, 133.4, 132.8, 116.1, 96.9, 78.0, 70.5, 52.9, 35.2, 27.6,24.7, 12.1. See FIG. 31. MS (ESI) m/z 294 [M+H]⁺.

Example 8 Synthesis of Compound (VI-1)

To a solution of compound V-1A (530 mg, 1.7 mmol) in THF/H₂O (1:1, 12mL) were added NMO (50% w/w aqueous solution, 750 μL, 3.4 mmol) and OsO₄(2.5% wt. % in 2-methyl-2-propanol, 1.1 mL, 0.085 mmol). The resultingmixture was stirred at RT for 17 hours. Then, NaIO₄ (250 mg, 1.16 mmol)was added to the above reaction mixture and stirred for additional 3 hrsat 25° C. The reaction mixture was quenched with saturated Na₂S₂O₃ (10mL) and saturated NaHCO₃ (10 mL) and extracted with CH₂Cl₂ (3×20 mL).The combined organic layer was dried over Na₂SO₄ and concentrated underreduced pressure. The crude product was purified by silica flashchromatography (1.25 cm ID×5 cm) using a solvent gradient of 19:1 (50mL) to 9:1 (50 mL) to 4:1 (50 mL) hexanes/EtOAc to afford compound VI-1(170 mg, 0.54 mmol, 94%) as a mixture of diastereomers. The compoundVI-1 was characterized by ¹H-NMR (CDCl₃, 500 MHz). See FIG. 12. MS (ESI)m/z 314 [M+H].

Example 9 Synthesis of Compound (VII-1)

To a solution of compound VI-1 (170 mg, 0.54 mmol) in dry CH₂Cl₂ (3 mL)was added BnOH (170 μl, 1.64 mmol) followed by BF₃.Et₂O (20 μl, 0.16mmol). The reaction mixture was stirred at 25° C. for 15 hours. ThenEt₃N (100 μl, 0.7 mmol) was added to the above reaction mixture whichwas directly concentrated, followed by silica flash column (1.25 cm ID×5cm) chromatography using a solvent gradient of 19:1 (50 mL) to 9:1 (50mL) to 4:1 (50 mL) hexanes/EtOAc to afford compound VII-1_(a) (83 mg,0.21 mmol) and compound VII-1_(b) (104 mg, 0.26 mmol). 86% total yieldof compound VII-1_(a) and compound VII-1_(b).

Compound VII-1_(a): ¹H-NMR (CDCl₃, 500 MHz) (δ): 7.30 (m, 5H), 5.24 (dd,J=4.4, 6.3 Hz, 1H), 4.77 (s, 1H), 4.72 (d, J=12.0 Hz, 1H), 4.64 (d,J=8.5 Hz, 1H), 4.45 (d, J=11.7 Hz, 1H), 4.17 (d, J=8.5 Hz, 1H), 3.78 (s,3H), 3.36 (d, J=8.5 Hz, 1H), 2.81 (ddd, J=1.0, 6.3, 14.2 Hz, 1H), 2.13(m, 1H), 1.37 (s, 3H), 0.86 (s, 9H). See FIG. 13.

Compound VII-1_(b): ¹H-NMR (CDCl₃, 500 MHz) (δ): 7.27 (m, 5H), 5.19 (d,J=5.0 Hz, 1H), 4.65 (d, J=11.4 Hz, 1H), 4.65 (d, J=8.5 Hz, 1H), 4.60 (s,1H), 4.45 (d, J=12.0 Hz, 1H), 4.21 (d, J=8.5 Hz, 1H), 3.76 (s, 3H), 3.17(d, J=8.5 Hz, 1H), 2.60 (d, J=13.2 Hz, 1H), 2.13 (m, 1H), 1.23 (s, 3H),0.82 (s, 9H). MS (ESI) m/z 404 [M+H]. See FIG. 14.

The structure of compound VII-1_(b) was confirmed by crystal structure,as shown in FIG. 15.

Example 10 Synthesis of Compound (VIII-1_(b))

To a solution of compound VII-1_(b) (40 mg, 0.1 mmol) in dry THF (2 mL)at −20° C. was added LiAlH₄ (2.0 M, 75 μl, 0.15 mmol). The reactionmixture was allowed to warm up to −5° C. in 10 min and stirred for anadditional 20 min. The reaction mixture was then quenched with saturatedaqueous potassium sodium tartrate (5 mL) and extracted with EtOAc (3×5ml). The combined organic layer was dried with MgSO₄ and concentratedunder reduced pressure to yield a crude product which was purified bysilica flash chromatography (column 1.25 cm ID×10 cm) using a solventgradient of 19:1 (50 mL) to 9:1 (100 mL) to 4:1 (200 mL) hexanes/EtOActo afford the product, compound VIII-1_(b) (19 mg, 0.051 mmol, 50%yield). The compound VIII-1_(b) was characterized by ¹H-NMR (CDCl₃, 500MHz). See FIG. 16. MS (ESI) m/z 376 [M+H].

Example 11 Synthesis of Compound (VIII-1_(a))

To a solution of compound VII-1_(a) (90 mg, 0.22 mmol) in dry THF (5 mL)was added lithium borohydride (2M solution in THF, 558 uL, 1.1 mmol,)and stirred at RT. After 15 minutes of stirring, methanol (100 uL) wasadded to the reaction mixture at RT (room temperature was maintained bycooling the reaction mixture with water bath). After 3 hours ofadditional stirring, the reaction mixture was quenched with H₂O (20 mL)and extracted with ethyl acetate (2×20 mL). The combined organic layerwas washed with brine (20 mL), dried over Na₂SO₄ and concentrated underreduced pressure to afford the product, compound VIII-1_(a) as clear oil(75 mg, 0.2 mmol, 90.9% yield), which can be used in the next stepwithout any column chromatography. The compound VIII-1_(a) wascharacterized by ¹H-NMR (CDCl₃, 500 MHz). See FIG. 17. MS (ESI) m/z 376[M+H] and 398 [M+Na].

Example 12 Synthesis of Compound (IX-1_(b))

To a solution of VIII-1_(b) (30 mg, 0.08 mmol) in dry CH₂Cl₂ (1 ml) wereadded NMO (28 mg, 0.24 mmol) and TPAP (3.0 mg, 0.008 mmol). Theresulting mixture was stirred at RT for 18 hours. The reaction mixturewas then concentrated and purified by silica flash chromatography(column 1.25 cm ID×10 cm) using a solvent gradient of 19:1 (50 mL) to9:1 (100 mL) to 17:3 (200 mL) hexanes/EtOAc to afford the product,compound IX-1_(b), as clear oil (27 mg, 0.072 mmol, 90% yield). Thecompound IX-1_(b) was characterized by ¹H-NMR (CDCl₃, 500 MHz). See FIG.18. MS (ESI) m/z 374 [M+H].

Example 13 Synthesis of Compound (IX-1_(a))

To a solution of alcohol, compound VIII-1_(a) (40 mg, 0.107 mmol) in dryCH₂Cl₂ (3 ml) were added NMO (37.5 mg, 0.32 mmol) and TPAP (3.78 mg,0.01 mmol). The reaction mixture was stirred at RT for 18 hours. Theabove reaction mixture was then concentrated and purified by silicaflash chromatography (column 2.5 cm ID×6 cm) using a solvent gradient of19:1 (50 mL) to 9:1 (100 mL) to 17:3 (200 mL) hexanes/EtOAc to affordthe product, compound IX-1_(a), as a white solid (34 mg, 0.091 mmol,85.5% yield). The compound IX-1_(a) was characterized by ¹H-NMR (CDCl₃,500 MHz). See FIG. 19. MS (ESI) m/z 374 [M+H] and 396 [M+Na].

Example 14 Synthesis of 9-Cyclohex-2-Enyl-9-Borabicyclo[3.3.1]Nonane

To a solution of 9-borabicyclo[3.3.1]nonane (9-BBN) in THF (0.5 M, 10.0ml, 5.0 mmol) was added 1,3-cyclohexadiene (97%) (490 μl, 5.0 mmol) andstirred for 24 hrs at RT to afford a solution of 9-cyclohex-2-enyl-9-BBNin THF (0.5 M) which was directly used to couple with compound offormula IX-1.

Example 15 Synthesis of Compound (X-1_(b)B)

To a solution of compound IX-1_(b) (20 mg, 0.053 mmol) in THF (0.5 ml)at −78° C. was added the 9-cyclohex-2-enyl-9-BBN solution (see Example12) in THF (0.5 M, 320 μl, 0.16 mmol). The reaction mixture was allowedto warm to RT over 1.5 hr and stirred for additional 10 hrs at RT.Ethylamine (16 μl, 0.265 mmol) was then added to the above reactionmixture, and stirring continued for an additional 16 hrs at RT. Thereaction mixture was then concentrated under reduced pressure and theresulting residue was purified by silica flash chromatography (column1.25 cm ID×10 cm) using a solvent gradient of 19:1 (50 mL) to 9:1 (100mL) to 17:3 (200 mL) hexanes/EtOAc to afford the product, compoundX-1_(b)B, as a white solid (17.0 mg, 0.037 mmol, 70.4%) which wascrystallized from hexanes/ethylether (1:1). The compound X-1_(b)B wascharacterized by ¹H-NMR (CDCl₃, 500 MHz), and ¹³C-NMR (CDCl₃, 125 MHz).See FIGS. 20 and 21. The structure of compound X-1_(b)B was confirmed byX-ray crystal structure. See FIG. 22. MS (ESI) m/z 456 [M+H] and 478[M+Na].

Example 16 Synthesis of Compound (X-1_(a)B)

To a solution of aldehyde, compound IX-1_(a), (60 mg, 0.161 mmol) in THF(2.0 mL) at −78° C. was added the 9-cyclohex-2-enyl-9-BBN solution inTHF (0.5 M, 0.96 mL, 0.48 mmol) and the reaction mixture was allowed towarm to RT over 1.5 hr and stirred for additional 10 hrs at RT.Ethylamine (50 μl, 0.81 mmol) was then added to the above reactionmixture, and stiffing continued for an additional 16 hrs at RT. Thereaction mixture was then concentrated under reduced pressure and theresulting residue was purified by silica flash chromatography (column1.25 cm ID×10 cm) using a solvent gradient of 19:1 (50 mL) to 9:1 (200mL) of hexanes/EtOAc to afford a pure product, a compound X-1_(a)B (52.0mg, 0.114 mmol, 70.9%). The compound X-1_(a)B was characterized by¹H-NMR (CDCl₃, 500 MHz), and ¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 23 and24. MS (ESI) m/z 456 [M+H] and 478 [M+Na].

Example 17 Synthesis of Compound (XXII-1)

To a solution of compound XVI-1B (3.5 mg, 11.2 μmol) in CH₂Cl₂ (1 ml) ina scintillation vial (20 ml) were added Dess-Martin periodinane (23.7mg; 56 μmol) and a magnetic stir bar. The reaction mixture was stirredat RT for about 16 hours. The progress of the reaction was monitored byanalytical HPLC. The reaction mixture was then filtered through amembrane filter (0.2 μm) and purified by normal phase HPLC using aPhenomenex Luna 10u Silica column (25 cm×21.2 mm ID), ELSD detector, asolvent gradient of 25% to 80% EtOAc/hexanes over 19 min, 80 to 100%EtOAc/hexanes over 1 min, holding at 100% EtOAc for 5 min, at a flowrate of 14.5 ml/min to afford a pure compound of formula XXII-1. ¹H NMR(DMSO-d₆, 500 MHz) δ 1.54 (s, 3H), 1.59 (m, 2H), 1.66-1.70 (m, 1H),1.73-1.80 (m, 1H), 1.96 (m, 2H), 2.0-2.11 (m, 2H), 3.09 (t, 1H, J=7.0Hz), 3.63 (brs, 1H), 3.83-3.88 (m, 1H), 3.89-3.93 (m, 1H), 5.50 (dd, 1H,J=2, 10 Hz), 5.92 (dd, 1H, J=2.5, 10 Hz), 9.70 (s, 1H, NH); MS (ESI),m/z 312 (M+H)⁺ and 334 (M+Na)⁺.

Example 18 Synthesis of Compound (XVI-1A) Via Chemical Reduction

The compound of formula XVI-1A was synthesized by reducing the ketogroup of the compound of formula XXII-1 with a common reducing agent(s)under various reaction conditions as shown in the Table 1.

TABLE 1^(a) Reaction Conditions Product Ratio   NaBH₄ # eq    Solvent^(b) Temp in ° C. Time in min

(XVI-1A)

(XVI-1B)

1 Monoglyme + 1% water −78 14 5 95 0 1 Monoglyme + 1% water −10 14 30 5020 1 Monoglyme + 1% water 0 14 33.3 33.3 33.3 2 Monoglyme + 1% water RT8 50 0 50 1 Monoglyme + 1% water RT 8 45 10 45 0.5 Monoglyme + 1% waterRT 8 50 50 0 0.25 Monoglyme + 1% water RT 8 50 50 0 1 IPA + 1% water RT10 50 0 50 0.5 IPA + 1% water RT 12 60 10 30 0.25 IPA + 1% water RT 8 5040 10 0.25 IPA + 5% water RT 8 10 0 10 0.5 IPA RT 8 40 50 10 0.5 IPA 0 830 70 0 0.25 IPA RT 8 No reaction 1 THF + 1% water RT 10 50 0 50 0.5THF + 1% water RT 12 50 50 0 0.25 THF + 1% water RT 8 30 70 0 1 + LiClMonoglyme + 1% water −78 10 5 95 0 1 + LiCl Monoglyme + 1% water 0 1027.2 36.4 36.4 1 + LiCl Monoglyme + 1% water 10 10 10 30 60 1 + CeCl₃Monoglyme + 1% water −78 10 5 95 0 1 + CeCl₃ Monoglyme + 1% water 0 1025 50 25 1 + CeCl₃ Monoglyme + 1% water 10 10 20 60 20 ^(a)Degradationor little to no product was observed using the following reagents. 1.NaBH₄ on 10%, Basic Al₂O₃, 2. K-Selectride, 3. KS-Selectride, 4.BTHF-(R)-CBS, 5. BTHF-(S)-CBS, 6. NaBH(OAc)₃, 7. (CH₃)₄NBH(OAc)₃, and 8.iPrMgCl; ^(b)Methyl and ethyl ester derivatives were formed when MeOHand EtOH was used, respectively.

Example 19 Synthesis of Compound (XVI-1A) from Compound (XXII-1) ViaEnzymatic Reduction

Method A: Compound XXII-1 was subjected to enzymatic reduction usingketoreductases KRED-EXP-C1A and KRED-EXP-B1 Y (BioCatalytics, PasadenaCalif.). 20 mM of compound XXII-1 (62 mg, added as a DMSO solution, 0.4mL), 60 mg of KRED-EXP-C1A or KRED-EXP-B1Y, 50 mM sodium formate 1 mMNAD+ and 30 mg of FDH-101 were dissolved in 10 mL of phosphate buffer(150 mM, pH 6.9). The reaction was stirred at 30° C. for 1 hour beforeit was extracted with EtOAc. The combined organic layers were evaporatedto dryness using a speed-vacuum giving the product, compound XVI-1A, asa solid white powder. HPLC analysis (C18 reverse phase column (ACE C18,5 m 150× 4/6 nm)) and NMR showed only the formation of XVI-1A, as shownin Table 2. Both KRED-EXP-C1A and KRED-EXP-B1Y showed product formation.No detectable formation of the other diastereomeric alcohol, compound offormula XVI-1B was observed.

TABLE 2 Ketoreductase XXII-1 XVI-1A XVI-1B KRED-EXP-C1A 18%¹ 82% Notdetected KRED-EXP-B1Y 21%¹ 79% Not detected ¹Includes a minor impuritysimilar to compound (XXII-1) in the calculated yield

Reactions (10-100 mg scale) were performed on KRED-EXP-C1A andKRED-EXP-B1Y using glucose and glucose dehydrogenase (GDH) as a cofactorrecycler at pH 6.9 (Method B is the optimized procedure). The productswere extracted with EtOAc and analyzed by HPLC. The results are shown inTable 3.

TABLE 3 % Con- version^(a,b) GDH from XXII-1 Ketoreductase #eq TimeXXII-1 to (mg) # eq (w/w) (w/w) % Solvent in water (h) XVI-1A 10 C1A 10.5 ~20% DMSO 1 70 10 C1A 1 0.1 ~20% DMSO 1 70 10 C1A 1 0.1 ~20% DMSO 285 10 C1A 1 0.1 ~20% DMSO 3 90 100 C1A 1 0.1 ~20% DMSO 1 70 100 C1A 10.1 ~20% DMSO 3 80^(c) 50 C1A 1 0.1 ~20% DMSO 4 90^(c) 10 B1Y 1 0.1 ~20%DMSO 1 90 10 B1Y 1 0.1  50% t-BuOAc 1 40 20 50 10 B1Y 1 0.1  50% n-BuOAc1  0 24 20 10 B1Y 1 0.1  50% TBME 1  5 24 80 10 B1Y 2 0.2 ~20% DMSO 0.6795 10 C1A 2 0.2 ~20% DMSO 0.67 70 20 B1Y 2 0.2 ~20% DMSO 0.67 95^(d) 50B1Y 2 0.2 ~20% DMSO 0.67 90^(e) ^(a)At pH 6.9 using GDH, NAD, glucose^(b)Based on HPLC analysis of organic extract ^(c)Recovered yield 40%after purification by flash column chromatography. Some decompositionproduct was detected in aqueous layer ^(d)Recovered yield 90% afterpurification by flash column chromatography ^(e)Recovered yield 85%after purification by crystallization

As shown in Table 3, when KRED-EXP-C1A ketoreductase was used, theconversion from XXII-1 to XVI-1A was 70% complete after 1 h on 10 mgscale. Based on HPLC analysis of the organic extract, the conversion was90% complete when the reaction time was increased to 3 h, but subsequentevaluation of the aqueous extract revealed that a portion of the producthad decomposed, which is an expected hydrolysis product that forms inaqueous solution. The decomposition product has the structure shownbelow. Decomposition was minimized when biphasic solutions (50% aqueoust-BuOAc, n-BuOAc, TBME) were used, but the percent conversion wasgenerally very low even with longer reaction times (20-24 h), except in50% aqueous TBME. Of the two ketoreductase, KRED-EXP-B1Y ketoreductasewas superior to KRED-EXP-C1A in the conversion of XXII-1 to XVI-1A.Doubling the concentrations of KRED-EXP-B1Y and GDH and decreasing thereaction time resulted in better yields and minimal decomposition ofproduct (2-5%).

Decomposition Product:

Method B: see Example 31.

Example 20 Synthesis of Compound (XXIII-1B) Via (X-1_(b)B)

Method A: To a solution of X-1_(b)B (400 mg, 0.88 mmol) in THF (20 mL)was added aqueous HCl (0.5 M, 2 mL). The reaction mixture was warmed to60° C. and stirred for 10 hrs at this temperature. The above reactionmixture was diluted with H₂O (20 mL), then extracted with EtOAc (2×20mL) and CH₂Cl₂ (3×20 mL). The combined organic phase was dried overMgSO₄ and concentrated under reduced pressure. The crude residue wasre-dissolved in THF/H₂O ((2:1; 22.5 mL), then NaBH₄ (100 mg, 2.63 mmol)was added and stirred at 25° C. for 30 min. The reaction mixture wasdiluted with H₂O (20 mL) and extracted with EtOAc (2×20 mL) and CH₂Cl₂(3×20 mL), and the organic phase was dried over MgSO₄ and concentratedunder reduced pressure to afford XXIII-1B as crude white solid (260 mg,81%) which can be used in the next step without purification. Thecompound XXIII-1B was characterized by ¹H-NMR (CDCl₃, 500 MHz), and¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 32 and 33. MS (ESI) m/z 368.3[M+H]⁺.

Method B: Sodium metal (Na, 30 mg, 1.30 mmol) was dissolved in liquidammonia (3 mL) at −78° C. and the resultant dark blue mixture wasstirred for 5 min. A solution of X-1_(b)B (30 mg, 0.066 mmol) in dry THF(0.5 ml) was slowly added to the above reaction mixture and stirred at−78° C. for an additional 2 hrs. Solid ammonium chloride (NH₄Cl, 40 mg)was added slowly to the reaction mixture, which was then allowed to warmto RT (by removing the dry ice-acetone cold bath). Ammonia wasevaporated during warm up. The white residue was washed with brine andextracted with EtOAc. The organic phase was concentrated to afford crudehemiacetal, which was directly used in the next reaction withoutpurification.

To a solution of the above hemiacetal in THF:H₂O (2:1; 1.5 mL) was addedNaBH₄ (8 mg, 0.20 mmol). The reaction mixture was stirred for 1 hr at RTand then diluted with brine and extracted with EtOAc. The organic phasewas dried with MgSO₄, concentrated under reduced pressure and purifiedby silica flash chromatography (EtOAc in hexanes, 10% to 30%) to affordtriol XXIII-1B as clear oil (18 mg, 0.049 mmol, 74.2% yield over twosteps). The compound XXIII-1B was characterized by ¹H-NMR (CDCl₃, 500MHz), and ¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 32 and 33. MS (ESI) m/z368.3 [M+H]⁺.

Example 21 Synthesis of Compound (XXIII-1B) Via (X-1_(a)B)

Sodium metal (Na, 20 mg, 0.88 mmol) was dissolved in liquid ammonia (3ml) at −78° C. and the resultant dark blue mixture was stirred for 5min. A solution of compound X-1_(a)B (20 mg, 0.044 mmol) in dry THF (0.5ml) was slowly added to the above reaction mixture and stirred at −78°C. for additional 2 hrs. Solid ammonium chloride (NH₄C1, 30 mg) wasadded slowly to the reaction mixture, which was then allowed to warm toRT (by removing the dry ice-acetone cold bath). Ammonia was evaporatedduring warm up. The white residue was washed with brine and extractedwith EtOAc. The organic phase was concentrated under reduced pressure toafford crude hemiacetal which was directly used in the next reactionwithout purification.

To a solution of the above hemiacetal in THF:H₂O (2:1; 1.5 ml) was addedNaBH₄ (5 mg, 0.13 mmol). The reaction mixture was stirred for 1 hr at RTand then diluted with brine and extracted with EtOAc. The organic phasewas dried with MgSO₄, concentrated under reduced pressure and purifiedby silica flash chromatography (EtOAc in hexanes, 10% to 30%) to affordtriol XXIII-1B as clear oil (11.3 mg, 0.031 mmol, 70% yield over twosteps). The ¹H-NMR (CDCl₃, 500 MHz) and ¹³C-NMR (CDCl₃, 125 MHz) spectrawere the same as shown FIGS. 32 and 33, respectively. MS (ESI) m/z 368.3[M+H].

Example 22 Synthesis of Compound (XXIV-1B) Via (XXIII-1b-Bz)

To a solution of XXIII-1B (120 mg, 0.33 mmol) in CH₂Cl₂ (5 mL) wereadded Et₃N (120 μl, 0.86 mmol) and benzoyl chloride (BzCl, 60 μl, 0.52mmol). The reaction mixture was stirred at 25° C. for 10 hrs. Then thereaction mixture was directly concentrated under reduced pressure andthe resulting product was purified by silica flash chromatography (EtOAcin hexanes, 10% to 30%) to afford XXIV-1B-Bz (136 mg, 0.29 mmol, 87%).The compound XXIV-1B-Bz was characterized by ¹H-NMR (CDCl₃, 500 MHz).See FIG. 34. MS (ESI) m/z 472.3 [M+H]⁺.

Example 23 Synthesis of Compound (XXV-1B-Bz) Via (XXIV-1B-Bz)

To a solution of XXIV-1B-Bz (136 mg, 0.29 mmol) in CF₃CH₂OH (2 mL) wereadded 1,3-propanedithiol (200 μl, 2 mmol) and a catalytic amount ofaqueous HCl (12N, 10 μL). The reaction mixture was stirred at 60° C. for3-4 hr, concentrated under reduced pressure and the resulting crudeproduct was then purified by silica flash chromatography (EtOAc inhexanes, 20% to 80%) to afford XXV-1B-Bz (110 mg, 0.27 mmol, 94%). Thecompound XXV-1B-Bz was characterized by ¹H-NMR (CDCl₃, 500 MHz), and¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 35 and 36. MS (ESI) m/z 404.3[M+H]⁺.

Example 24 Synthesis of Compound (XXVp-1B-Bz-TMS) Via (XXV-1B-Bz)

To a solution of XXV-1B-Bz (70 mg, 0.17 mmol) in CH₂Cl₂ (2 mL) wereadded Et₃N (480 μL, 3.47 mmol) and TMSCl (220 μL, 1.74 mmol) and thesolution was stirred at 25° C. for 12 hrs. The reaction was quenchedwith saturated aqueous NaHCO₃ (5 mL) and extracted with CH₂Cl₂ (3×5 mL).The combined organic phase was dried over MgSO₄, concentrated underreduced pressure and then purified by silica flash chromatography (EtOAcin hexanes, 20% to 80%) to afford XXVp-1B-Bz-TMS (44 mg, 0.093 mmol, 53%yield). The compound XXVp-1B-Bz-TMS was characterized by ¹H-NMR (CDCl₃,500 MHz), and ¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 37 and 38. MS (ESI)m/z 476.3 [M+H]⁺.

Example 25 Synthesis of Compound (XXVI-1B-Bz) Via (XXVp-1B-Bz-TMS)

To a solution of XXVp-1B-Bz-TMS (120 mg, 0.25 mmol) in CH₂Cl₂ (5 mL) wasadded Dess-Martin periodinane (118 mg, 0.278 mmol) and the reactionmixture was stirred at 25° C. for 2 hrs. The reaction was quenched withsaturated aqueous Na₂S₂O₃ (3 mL) and saturated aqueous NaHCO₃ (2 mL) andextracted with CH₂Cl₂ (2×5 mL). The combined organic phase was driedover MgSO₄ and concentrated under reduced pressure to afford the crudealdehyde as a white powder which was used for the next step withoutpurification.

To a solution of the above freshly prepared aldehyde in t-BuOH/H₂O (2:1;4.5 mL) was added NaH₂PO₄ (400 mg, 3.33 mmol) and the reaction mixturewas cooled to 0° C. Then 2-methyl-2-butene (2M in THF, 3.70 mL, 7.57mmol) and NaClO₂ (175 mg, 1.93 mmol) were added sequentially and stirredat 0° C. for 1.5 hrs. The reaction mixture was then diluted with brine(5 mL) and extracted with EtOAc (2×5 mL). The aqueous phase wasacidified with HCl (0.5 M) to pH 3.0 and extracted with CH₂Cl₂ (3×5 mL).The combined organic phase was dried over MgSO₄ and concentrated underreduced pressure to yield a white solid residue which was purified byreversed phase HPLC using an ACE 5μ C18 column (150×21 mm ID) and asolvent gradient of 10% to 100% CH₃CN/H₂O/0.05% TFA over 22 min, holdingat 100% CH₃CN/0.05% TFA for 3 min at a flow rate of 14.5 mL/min toafford the carboxylic acid XXVI-1B-Bz (66 mg, 0.16 mmol, 62.6% yieldover two steps). The carboxylic acid XXVI-1B-Bz was characterized by¹H-NMR (CD₃OD, 500 MHz), and ¹³C-NMR (CD₃OD, 125 MHz). See FIGS. 39 and40. MS (ESI) m/z 418.2 [M+H]⁺.

Example 26 Synthesis of Compound (XV-1B) Via (XXVI-1B-Bz)

Method A: 1) K₂CO₃, MeOH; H⁺; 2) TBSCl, imid.; 3) BOPCl; 4) HF.Pyr

To a solution of XXVI-1B-Bz (14 mg, 0.033 mmol) in MeOH (0.5 ml) wasadded K₂CO₃ (14 mg, 0.10 mmol) and the reaction mixture was stirred at25° C. for 15 hrs. Then aqueous HCl (200 μl, 1.0 M) was added to thisreaction mixture which was directly concentrated and dried under highvacuum to afford XXVII-1B in which the benzoyl group has been replacedby hydrogen as a white residue, which was directly used in the next stepwithout further purification.

To a solution of the product obtained from the previous step in CH₂Cl₂(0.50 ml) were added imidazole (7.0 mg, 0.10 mmol) and TBSCl (10 mg,0.066 mmol) and the mixture was stirred at 25° C. for 10 hrs. Then thereaction mixture was directly concentrated under reduced pressure anddried well by high vacuum to afford XXVI-1B-TBS a white residue, whichwas directly used in the next step without further purification.

To a solution of XXVI-1B-TBS in CH₃CN (0.40 ml) were added pyridine(0.40 ml) and BOPCl (17 mg, 0.066 mmol) and the reaction mixture wasstirred at 25° C. for 16 hrs. Then the reaction mixture was concentratedunder reduced pressure and the products purified by silica gelchromatography using EtOAc/hexanes gradients (20% to 80%) to afford theXXVIII-1B-TBS (5.0 mg; ¹H-NMR (CDCl₃, 500 MHz) See FIG. 41) and XV-1B(3.0 mg) as white solid.

To a solution of the above XXVIII-1B-TBS (5.0 mg) in THF (0.5 ml) wereadded pyridine (30 μl) and HF⁻ pyridine (30 μl) and the reaction mixturewas stirred at 25° C. for 2 hrs in a plastic tube. Then the reactionmixture was quenched with saturated aqueous NaHCO₃ (1 ml) and extractedwith CH₂Cl₂ (3×1.0 ml). The organic phase was dried over MgSO₄,concentrated under reduced pressure and purified by silica gel flashchromatography using a EtOAc/hexanes gradient (20% to 80%) to affordXV-1B (4.0 mg, 0.013 mmol). Overall Yield=73%. The compound XV-1B wascharacterized by ¹H-NMR (acetone-d₆, 500 MHz), and ¹³C-NMR (acetone-d₆,125 MHz). See FIGS. 42 and 43. MS (ESI) m/z 296 [M+H]⁺.

Method B: 1) K₂CO₃, MeOH; H⁺; 2) TESCl, imid.; 3) BOPCl; 4) HF.Pyr 28%

To a solution of XXVI-1B-Bz (240 mg, 0.575 mmol) in MeOH (3.0 ml) wasadded K₂CO₃ (240 mg, 1.74 mmol) and the reaction mixture was stirred at25° C. for 15 hrs. Then aqueous HCl (600 μl, 1.0 M) was added to thisreaction mixture which was directly concentrated and dried under highvacuum to afford XXVII-1B as a white residue, which was directly usedfor the next step without further purification.

To a solution of the product obtained from the previous step in CH₂Cl₂(5.0 ml) was added imidazole (195 mg, 2.87 mmol) and TESCl (0.39 ml,2.30 mmol) and the reaction mixture was stirred at 25° C. for 18 hrs.Then the reaction mixture was directly concentrated under reducedpressure and dried well by high vacuum to afford XXVI-1B-TES as a whiteresidue, which was directly used in the next step without furtherpurification.

To a solution of XXVI-1B-TES in CH₃CN (3.0 ml) were added pyridine (3.0ml) and BOPCl (290 mg, 1.15 mmol) and the reaction mixture was stirredat 25° C. for 18 hrs. Then the reaction mixture was filtered through ashort silica-plug; the filtrate was concentrated under reduced pressureand dried by high vacuum to afford TES-β-lactone XXVIII-1B-TES as awhite residue, which was directly used in the next step without furtherpurification.

To a solution of the above TES-β-lactone residue (XXVIII-1B-TES) in THF(5.0 ml) were added pyridine (150 μl) and HF.pyridine (150 μl) and thereaction mixture was stirred at 25° C. for 5-6 hrs in a plastic tube.Then the reaction mixture was quenched with saturated aqueous NaHCO₃ (10ml) and extracted with CH₂Cl₂ (3×10 ml). The organic phase was driedover MgSO₄, concentrated under reduced pressure and purified by silicaflash chromatography (EtOAc in hexanes, 10% to 80%) to afford β-lactoneXV-1B (47.0 mg, 0.16 mmol). Overall Yield=28%.

Example 27 Synthesis of Compound (XVI-1B) Via (XV-1B)

To a solution of XV-1B (35 mg, 0.118 mmol) obtained from Example 26 inCH₃CN (250 μl) were added pyridine (250 μl) and Ph₃PCl₂ (80 mg, 0.24mmol) and the reaction mixture was stirred at RT for 18 hrs. Then thereaction mixture was concentrated under reduced pressure and purified bysilica gel flash chromatography using a EtOAc/hexanes gradient (5% to20%) to afford XVI-1B (21 mg, 57% yield). The compound XVI-1B wascharacterized by ¹H-NMR (CDCl₃, 500 MHz) and ¹³C-NMR (CDCl₃, 125 MHz).See FIGS. 44 and 45. MS (ESI) m/z 314 [M+H]⁺. MS (ESI) m/z 314 [M+H]⁺.HRMS (ESI) m/z 314.1151 [M+H]⁺ (calcd for C₁₅H₂₁ClNO₄, 314.1159, Δ=−2.4ppm).

Example 28 Synthesis of Compound (XXII-1) Via (XVI-1B)

To a solution of compound XVI-1B (10 mg, 32 μmol) obtained from Example27 in CH₂Cl₂ (4 mL) in a round bottom flask (25 mL) were addedDess-Martin periodinane (20.35 mg, 48 μmol) and a magnetic stir bar. Thereaction mixture was stirred at RT for about 2 hours then quenched withsaturated aqueous Na₂S₂O₃ (5 ml) and saturated aqueous NaHCO₃ (5 ml),and then extracted with CH₂Cl₂ (2×5 ml). The organic phase was driedover Na₂SO₄ and concentrated under reduced pressure. The resulting crudeproduct was then purified by silica flash column (0.4 cm ID×3 cm)chromatography using a solvent gradient of 19:1 (5 mL) to 9:1 (5 mL) to17:3 (5 mL) to 4:1 (10 mL) hexanes/EtOAc to afford XXII-1 (6 mg, 19.3μmol, 60.3% yield). The compound XXII-1 was characterized by ¹H NMR(CDCl₃, 500 MHz). See FIG. 46. MS (ESI), m/z 312 [M+H]⁺ and 334 [M+Na]⁺.

Example 29 Synthesis of Compound (XVI-1A) Via (XXII-1) by EnzymaticReduction

To a solution of XXII-1 (6 mg, 19.3 μmol) in DMSO (0.4 mL) obtained fromExample 28 in a round bottom flask (25 mL), 600 μL of potassiumphosphate buffer (150 mM, pH 6.9), 12 mg of ketoreductase KRED-EXP-B1Y,1.2 mg of glucose dehydrogenase (GDH), 300 μL of glucose (50 mM) and 300μL of NAD (1 mM) were added. The above reaction mixture was stirred at37-39° C. for about 40 min and then extracted with EtOAc (2×10 mL); thecombined organic phase was dried over Na₂SO₄ and concentrated underreduced pressure. This afforded about 5 mg of XVI-1A. (82.7% yield) as acrude product which was further purified by normal phase HPLC using aPhenomenex Luna 10μ Silica column (25 cm×21.2 mm ID) using a solventgradient of 25% to 80% EtOAc/hexanes over 19 min, 80 to 100%EtOAc/hexanes over 1 min, holding at 100% EtOAc for 5 min, at a flowrate of 14.5 mL/min and monitoring the purification by evaporative lightscattering detection (ELSD) to afford 2 mg of pure XVI-1A. [α]_(D)−70°(c 0.05, CH₃CN). The compound XVI-1A was characterized by ¹H-NMR(DMSO-d₆, 500 MHz) and ¹³C-NMR (DMSO-d₆, 125 MHz). See FIGS. 47 and 49.The ¹H NMR spectra were in complete agreement with those of an authenticsample of XVI-1A (FIGS. 48 and 50 respectively). MS (ESI) m/z 314[M+H]⁺. HRESIMS m/z 314.1173 [M+H]⁺ (calcd for C₁₅H₂₁ClNO₄, 314.1159,Δ=4.5 ppm).

Example 30 Synthesis of Compound (XXII-1) Via (XVI-1B) (Obtained as aSemisynthetic Derivative of a Fermentation Product of Salinospora)

To a solution of XVI-1B (75 mg, 0.24 mmol) (obtained as a semi-syntheticderivative of XVI-1A, which was obtained by fermentation of Salinosporatropica as disclosed in U.S. Pat. No. 7,176,232, issued Feb. 13, 2007,which is hereby incorporated by reference in its entirety) in CH₂Cl₂ (35mL) in a round bottom flask (150 mL) were added Dess-Martin periodinane(202.5 mg; 0.48 mmol) and a magnetic stir bar. The reaction mixture wasstirred at RT for about 3 hours, over which the progress of the reactionwas monitored by analytical HPLC. The reaction mixture was then quenchedwith saturated aqueous Na₂S₂O₃ (40 ml) and saturated aqueous NaHCO₃ (40ml), and extracted with CH₂Cl₂ (2×40 ml). The organic phase was driedover Na₂SO₄ and concentrated by reduced pressure to afford XXII-1 (70mg, 0.22 mmol, 94% yield). ¹H NMR (DMSO-d₆, 500 MHz) δ 1.54 (s, 3H),1.59 (m, 2H), 1.66-1.70 (m, 1H), 1.73-1.80 (m, 1H), 1.96 (m, 2H),2.0-2.11 (m, 2H), 3.09 (t, 1H, J=7.0 Hz), 3.63 (brs, 1H), 3.83-3.88 (m,1H), 3.89-3.93 (m, 1H), 5.50 (dd, 1H, J=2, 10 Hz), 5.92 (dd, 1H, J=2.5,10 Hz), 9.70 (s, 1H, NH); MS (ESI), m/z 312 [M+H]⁺ and 334 [M+Na]⁺.

Example 31 Synthesis of Compound (XVI-1A) Via (XXII-1) by EnzymaticReduction

To a solution of XXII-1 (50 mg, 0.16 mmol) obtained from Example 30 inDMSO (1 mL) in a round bottom flask (25 mL), 5 mL of potassium phosphatebuffer (150 mM, pH 6.9), 100 mg of ketoreductase KRED-EXP-B1Y, 10 mg ofglucose dehydrogenase (GDH), 2.5 mL of glucose (50 mM) and 2.5 mL of NAD(1 mM) were added. The above reaction mixture was stirred at 37-39° C.for 40 min and then extracted with EtOAc (2×25 mL); the combined organicphase was dried over Na₂SO₄ and concentrated under reduced pressure toyield a crude product which was crystallized in 1:1 acetone:heptane (6mL) in a 20 mL scintillation vial (by slow evaporation under nitrogengas) to afford XVI-1A as white crystalline solid (42 mg, 0.13 mmol, 85%yield). The structure of XVI-1A was confirmed by comparison of its mp,specific rotation and ¹H- and ¹³C-NMR spectra with those of an authenticsample.

Example 32 Synthesis of 2-Cyclohexenyl Zinc Chloride

To a solution of 1,3-cyclohexadiene (0.96 g, 12 mmol, d=0.84, 1143 uL)and Pd(PPh₃)₄ (462.2 mg, 0.4 mmol) in benzene (10 mL) under nitrogenatmosphere, was added Bu₃SnH (1.16 g, 4 mmol, d=1.098, 1.06 mL) dropwiseat room temperature and stirred for 15 minutes. After the solvent wasremoved on rotavap, the product was purified on silica flashchromatography (column 1.5 cm ID×20 cm) using a solvent gradient of 10:0(100 mL) to 19:1 (100 mL) to 9:1 (100 mL) of hexanes/EtOAc to affordcyclohexenyltributyltin (3.5 g, 9.4 mmol, 78.6% yield) as a clearliquid. Cyclohexenyltributyltin was characterized by ¹H-NMR (CDCl₃, 500MHz). See FIG. 51.

To a solution of cyclohenexyltributyltin (0.92 g, 2.5 mmol) in THF (5mL) at −78° C. under nitrogen was added nBuLi (1 mL, 2.5 M solution inhexane, 2.5 mmol). After an additional 30 min stifling, ZnCl₂ (340 mg,2.5 mmol, dissolved in 2 ml of THF) was added and stirring was continuedfor 30 min at −78° C. to afford 2-cyclohexenyl zinc chloride.

Example 33 Synthesis of Compound X-1_(a)

To a solution of IX-1_(a) (30 mg, 0.08 mmol) in 5 mL of THF at −78° C.,1 mL of cyclohexenyl zinc chloride (freshly prepared; Example 32) wasadded and stirred at −78° C. for about 3 hrs. The reaction was quenchedwith H₂O (15 mL) and extracted with EtOAc (2×15 mL). The combinedorganic phase was dried over anhydrous Na₂SO₄ and concentrated underreduced pressure to yield the crude product which was purified by silicaflash chromatography (column 2.5 cm ID×6 cm) using a solvent gradient of19:1 (50 mL) to 9:1 (50 mL) to 17:3 (50 mL) to 8:2 (50 mL) to 7:3 (50mL) of hexanes/EtOAc to afford pure cyclohexene derivative X-1_(a) (26mg, 0.057 mmol, 71.4% yield). The compound X-1_(a) was characterized by¹H-NMR (CDCl₃, 500 MHz), and ¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 52 and53. MS (ESI) m/z 456.3 [MH]⁺ and 478.3 [M+Na]⁺.

Example 34 Synthesis of Compound X-1_(b)

To a solution of IX-1_(b) (35 mg, 0.094 mmol) in 5 mL of THF at −78° C.,1.2 mL of cyclohexenyl zinc chloride (freshly prepared; Example 32) wasadded and stirred at −78° C. for about 3 hrs. The reaction was quenchedwith H₂O (15 mL) and extracted with EtOAc (2×20 mL). The combinedorganic phase was dried over anhydrous Na₂SO₄ and concentrated underreduced pressure to yield a liquid residue. This residue was dissolvedin 5 mL of hexanes and allowed to stand for an hour. A white solid wasprecipitated from the residue, which was separated by decanting thesolvent. The solid material was further washed with hexanes (2×2 mL) anddried on high-vacuum to afford pure X-1_(b) (32 mg, 0.066 mmol, 75%yield). The compound X-1_(b) was characterized by ¹H-NMR (CDCl₃, 500MHz), and ¹³C-NMR (CDCl₃, 125 MHz). See FIGS. 54 and 55. MS (ESI) m/z456.3 [M+H]⁺ and 478.3 [M+Na]⁺. The stereochemistry was determined byX-ray crystallography (See FIG. 56).

Example 35 In Vitro Inhibition of 20S Proteasome Activity by CompoundXVI-1A Obtained from Synthetic and Fermentation Sources

The compound XVI-1A as obtained synthetically using a method describedherein and by fermentation as described in U.S. Pat. No. 7,144,723,which is hereby incorporated by reference in its entirety. Both thesynthetic and fermentation compounds XVI-1A were prepared as 20 mM stocksolution in DMSO and stored in small aliquots at −80° C. Purified rabbitmuscle 20S proteasome was obtained from Boston Biochem (Cambridge,Mass.). To enhance the chymotrypsin-like activity of the proteasome, theassay buffer (20 mM HEPES, pH7.3, 0.5 mM EDTA, and 0.05% Triton X100)was supplemented with SDS resulting in a final SDS concentration of0.035%. The substrate used was suc-LLVY-AMC, a fluorogenic peptidesubstrate specifically cleaved by the chymotrypsin-like activity of theproteasome. Assays were performed at a proteasome concentration of 1μg/ml in a final volume of 200 μl in 96-well Costar microtiter plates.Both the synthetic and fermentation compounds XVI-1A were tested aseight-point dose response curves with final concentrations ranging from500 nM to 158 pM. After addition of test compounds to the rabbit 20Sproteasomes, the samples were preincubated at 37° C. for five minutes ina temperature controlled Fluoroskan Ascent 96-well microplate reader(Thermo Electron, Waltham, Mass.). During this preincubation step, thesubstrate was diluted 25-fold in SDS-containing assay buffer. After thepreincubation period, the reactions were initiated by the addition of 10μl of the diluted substrate and the plates were returned to the platereader. The final concentration of substrate in the reactions was 20 μM.Fluorescence of the cleaved peptide substrate was measured at λ_(ex)=390nm and λ_(em)=460 nm. All data were collected every five minutes for 2hour and plotted as the mean of duplicate data points. The IC₅₀ values(the drug concentration at which 50% of the maximal relativefluorescence is inhibited) were calculated by Prism (GraphPad Software)using a sigmoidal dose-response, variable slope model. To evaluate theactivity of the compounds against the caspase-like activity of the 20Sproteasome, reactions were performed as described above except thatZ-LLE-AMC was used as the peptide substrate. Both the synthetic andfermentation compounds XVI-1A were tested at concentrations ranging from5 μM to 1.6 nM. For the evaluation of these compounds against thetrypsin-like activity of the 20S proteasome, the SDS was omitted fromthe assay buffer and Boc-LRR-AMC was used as the peptide substrate. Theconcentration of the test compounds used in these assays ranged from 500nM to 158 pM.

Results (IC₅₀ values) shown in Table 4 and in FIGS. 57-59 illustratethat both synthetic and fermentation compounds XVI-1A have similarinhibitory activity against the chymotrypsin-like, trypsin-like andcaspase-like activities of the 20S proteasome in vitro.

TABLE 4 IN VITRO INHIBITION OF PURIFIED RABBIT 20S PROTEASOMES BY THESYNTHETIC AND FERMENTATION COMPOUNDS OF FORMULA XVI-1A IC₅₀ Values (nM)Compound XVI-1A Chymotrypsin-like Trypsin-like Caspase-like Fermentation2.6 35 387 Synthetic 3.2 37 467

Example 36 Effects on the Chymotrypsin-Like Activity of Proteasomes inRPMI 8226 Cells by Compounds XVI-1A Obtained from Synthetically and fromFermentation

RPMI 8226 (ATCC, CCL-155), the human multiple myeloma cell line, wascultured in RPMI 1640 medium supplemented with 2 mM L-Glutamine, 1%Penicillin/Streptomycin, 10 mM HEPES and 10% Fetal Bovine Serum at 37°C., 5% CO₂ and 95% humidified air. To evaluate the inhibitory effects onthe chymotrypsin-like activity of the 20S proteasome, test compoundsprepared in DMSO were appropriately diluted in culture medium and addedto 1×10⁶/ml RMPI 8226 cells at final concentration of 1, 5 or 10 nM.DMSO was used as the vehicle control at a final concentration of 0.1%.Following 1 hr incubation of RMPI 8226 cells with the compounds, thecells were pelleted by centrifugation at 2,000 rpm for 10 sec at roomtemperature and washed 3× with ice-cold 1× Dubach's Phosphate-BufferedSaline (DPBS, Mediatech, Herndon, Va.). DPBS washed cells were lysed onice for 15 min in lysis buffer (20 mM HEPES, 0.5 mM EDTA, 0.05% TritonX-100, pH 7.3) supplemented with protease inhibitor cocktail (RocheDiagnostics, Indianapolis, Ind.). Cell debris was pelleted bycentrifugation at 14,000 rpm for 10 min, 4° C. and supernatants (=celllysates) were transferred to a new tube. Protein concentration wasdetermined by the BCA protein assay kit (Pierce Biotechnology, Rockford,Ill.). The chymotrypsin-like activity of the 20S proteasome in the RPMI8226 cell lysates was measured by using the Suc-LLVY-AMC fluorogenicpeptide substrate in the proteasome assay buffer (20 mM HEPES, 0.5 mMEDTA, pH 8.0) containing a final concentration of 0.035% SDS. Thereactions were initiated by the addition of 10 μL of 0.4 mM Suc-LLVY-AMC(prepared by diluting a 10 mM solution of the peptide in DMSO 1:25 withassay buffer) to 190 μL of the cell lysates in 96-well Costar microtiterplate and incubated in the Thermo Lab Systems Fluoroskan plate reader at37° C. Fluorescence of the cleaved peptide substrate was measured atλ_(ex)=390 nm and λ_(em)=460 nm. All data were collected every fiveminutes for 2 hour. The total protein used for each assay was 20 μg. Thefinal concentration of Suc-LLVY-AMC and DMSO was 20 μM and 0.2%,respectively. After subtraction of the background (the values from wellscontaining buffer and substrate in the absence of cell lysate), theactivity of test compound was expressed as % inhibition as normalized tothe proteasome activity observed in the DMSO treated control cells.

Results in Table 5 show that exposure of RPMI 8226 cells to thefermentation or synthetic compounds XVI-1A resulted in a dose-dependentinhibition of the 20S proteasome chymotrypsin-like activity. Inaddition, a similar inhibition profile was observed when cells wereexposed to compound XVI-1A obtained via fermentation or to compoundXVI-1A obtained synthetically.

TABLE 5 INHIBITION OF THE CHYMOTRYPSIN-LIKE ACTIVITY OF PROTEASOME INRPMI 8826 CELLS BY SYNTHETIC AND FERMENTATION COMPOUNDS XVI-1A %inhibition of the 20S proteasome chymotrypsin-like activity in RPMI 8826cells Concentration (nM) Fermentation Synthetic 1 38 32 5 86 79 10 97 96

The examples described above are set forth solely to assist in theunderstanding of the embodiments. Thus, those skilled in the art willappreciate that the methods may provide derivatives of compounds.

One skilled in the art would readily appreciate that the presentinvention is well adapted to carry out the objects and obtain the endsand advantages mentioned, as well as those inherent therein. The methodsand procedures described herein are presently representative ofpreferred embodiments and are exemplary and are not intended aslimitations on the scope of the invention. Changes therein and otheruses will occur to those skilled in the art which are encompassed withinthe spirit of the invention.

It will be readily apparent to one skilled in the art that varyingsubstitutions and modifications can be made to the embodiments disclosedherein without departing from the scope and spirit of the invention.

All patents and publications mentioned in the specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

The invention illustratively described herein suitably can be practicedin the absence of any element or elements, limitation or limitationswhich is not specifically disclosed herein. The terms and expressionswhich have been employed are used as terms of description and not oflimitation, and there is no intention that in the use of such terms andexpressions indicates the exclusion of equivalents of the features shownand described or portions thereof. It is recognized that variousmodifications are possible within the scope of the invention. Thus, itshould be understood that although the present invention has beenspecifically disclosed by preferred embodiments and optional features,modification and variation of the concepts herein disclosed can beresorted to by those skilled in the art, and that such modifications andvariations are considered to be falling within the scope of theembodiments of the invention.

1. A compound of formula (X):

wherein: R₁ is hydrogen or substituted or unsubstituted C₁₋₆ alkyl; R₃is selected from the group consisting of substituted or unsubstitutedvariants of the following: C₁₋₆ alkyl, C₃₋₆ cycloalkyl, C₂₋₆ alkenyl,C₃₋₆ cycloalkenyl, aryl, and arylalkyl; R₄ can be selected from thegroup consisting of substituted or unsubstituted variants of thefollowing: C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₃-C₁₂cycloalkyl, C₃-C₁₂ cycloalkenyl, C₃-C₁₂ cycloalkynyl, C₃-C₁₂heterocyclyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl,(cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl, acylalkyl,alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido, azidoalkyl,aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of carboxyalkyl,alkylaminoalkyl, salt of an alkylaminoalkyl, dialkylaminoalkyl, salt ofa dialkylaminoalkyl, phenyl, alkylthioalkyl, arylthioalkyl, carboxy,cyano, alkanesulfonylalkyl, alkanesulfinylalkyl, alkoxysulfinylalkyl,thiocyanoalkyl, boronic acidalkyl, boronic esteralkyl, guanidinoalkyl,salt of a guanidinoalkyl, sulfoalkyl, salt of a sulfoalkyl,alkoxysulfonylalkyl, sulfooxyalkyl, salt of a sulfooxyalkyl,alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of a phosphonooxyalkyl,(alkylphosphooxy)alkyl, phosphorylalkyl, salt of a phosphorylalkyl,(alkylphosphoryl)alkyl, pyridinylalkyl, salt of a pyridinylalkyl, saltof a heteroarylalkyl and halogenated alkyl including polyhalogenatedalkyl; and PG₁ is a protecting group moiety.
 2. The compound claim 1,wherein PG₁ is selected from the group consisting of benzyl, asubstituted benzyl, an alkylcarbonyl, an arylalkylcarbonyl, asubstituted methyl ether, a substituted ethyl ether, a substitutedbenzyl ether, a tetrahydropyranyl ether, a silyl ether, an ester, and acarbonate.
 3. The compound of claim 1, wherein R₄ is 2-cyclohexenyl. 4.The compound of claim 1, wherein R₃ is methyl.
 5. The compound of claim1, wherein R₁ is a substituted or unsubstituted C₁₋₆ alkyl.
 6. Thecompound of claim 1, wherein the compound of formula (X) has thestructure:


7. The compound of claim 1, wherein the compound of formula (X) has thestructure:


8. The compound of claim 1, wherein the compound of formula (X) has thestructure:


9. The compound of claim 1, wherein the compound of formula (X) has thestructure:


10. A method of forming a compound of formula (XV) from the compound ofclaim 1 comprising the steps of: cleaving an aminal group; removing PG₁and reductively opening the hemiacetal, wherein PG₁ is a protectinggroup moiety; and forming a four membered lactone ring; wherein thecompound of formula (XV) has the following structure:

wherein the compound of formula (X) has the following structure:


11. The method of claim 10, wherein the cleaving of the aminal group isbefore the removal of PG₁ and reductively opening the hemiacetal, andbefore the formation of the four membered lactone ring.
 12. The methodof claim 10, wherein the cleaving of the aminal group is after theremoval of PG₁ and reductively opening the hemiacetal, but before theformation of the four membered ring.
 13. The method of claim 10, furthercomprising substituting the primary hydroxy group of the compound offormula (XV) to form a compound of formula (XVI), wherein the compoundof formula (XVI) has the following structure:

wherein X is a halogen.
 14. The method of claim 10, further comprisingsubstituting the primary hydroxy group of the compound of formula (XV)to form a compound of formula (XVI-B), wherein the compound of formula(XVI-B) has the following structure:

wherein X is a halogen.
 15. The method of claim 14, further comprisingthe steps of: (1) oxidizing the secondary hydroxy group of the compoundof formula (XVI-B) wherein the compound of formula (XVI-B) has thefollowing structure:

to form a compound of formula (XXII):

(2) reducing the keto group of the compound of formula (XXII) to form acompound of formula (XVI-A), wherein the compound of formula (XVI-A) hasthe following structure:


16. The method of claim 14, further comprising the step of: (1)inverting the stereochemistry of the secondary hydroxy carbon center ofthe compound of formula (XVI-B), wherein the compound of formula (XVI-B)has the following structure:

to form a compound of formula (XVI-A), wherein the compound of formula(XVI-A) has the following structure:


17. A method of preparing the compound of claim 1 comprising adding R₄to the compound of formula (IX) by reacting the compound of formula (IX)with an organometallic moiety containing at least one R₄ to form acompound of formula (X):


18. The method of claim 17, wherein the organometallic moiety is9-cyclohex-2-enyl-9-borabicyclo[3.3.1]nonane.
 19. The method of claim17, wherein the compound of formula (IX) has the structure:

the compound of formula (X) has the structure:


20. The method of claim 17, wherein the compound of formula (IX) has thestructure:

the compound of formula (X) has the structure:


21. The method of claim 17, wherein the compound of formula (IX) has thestructure:

the compound of formula (X) has the structure:


22. The method of claim 17, wherein the compound of formula (IX) has thestructure:

the compound of formula (X) has the structure:


23. A method of preparing a compound of formula (XXIII) comprisingremoving the protecting group moiety on the compound of claim 1 andreductively opening the hemiacetal to form a compound of formula(XXIII):


24. The method of claim 23, wherein the compound of formula (X) has thestructure:

the compound of formula (XXIII) has the structure:


25. The method of claim 23, wherein the compound of formula (X) has thestructure:

the compound of formula (XXIII) has the structure:


26. The method of claim 23, wherein the compound of formula (X) has thestructure:

the compound of formula (XXIII) has the structure:


27. The method of claim 23, wherein the compound of formula (X) has thestructure:

the compound of formula (XXIII) has the structure:


28. A method of preparing a compound of formula (Xp) comprisingprotecting the C-5 secondary hydroxy group of the compound of claim 1with a suitable protecting group moiety to form a compound of formula(Xp):

wherein PG₂ is a protecting group moiety.
 29. The method of claim 28,further comprising cleaving the aminal of the compound of formula (Xp)with an acid to form a compound of formula (XIp):


30. A method of preparing a compound of formula (XI) comprising cleavingthe aminal of the compound of claim 1 with an acid to form a compound offormula (XI):


31. A method of preparing a compound of formula (XVII) comprisingoxidizing the secondary alcohol group of the compound of claim 1 to forma compound of formula (XVII):